方法一：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Web.Services.Description;
using Microsoft.CSharp;
using System.CodeDom.Compiler;
using System.CodeDom;
using System.Net;

namespace WebServiceClient
{
    public class WebServiceHelper
    {
        
 
/// <summary>  
        /// 動態呼叫WebService  
        /// </summary>  
        /// <param name="url">WebService地址</param>  
        /// <param name="classname">類名</param>  
        /// <param name="methodname">方法名(模組名)</param>  
        /// <param name="args">引數列表</param>
 
  
        /// <returns>object</returns> 
        public static object InvokeWebService(string url, string classname, string methodname, object[] args)
        {
            string @namespace = "ServiceBase.WebService.DynamicWebLoad";
            if (classname == null || classname == "")
            {
                classname 
 
= WebServiceHelper.GetClassName(url);
            }
            //獲取服務描述語言(WSDL)  
            WebClient wc = new WebClient();
            Stream stream = wc.OpenRead(url + "?WSDL");
            ServiceDescription sd = ServiceDescription.Read(stream);
            ServiceDescriptionImporter sdi = new ServiceDescriptionImporter();
            sdi.AddServiceDescription(sd, "", "");
            CodeNamespace cn = new CodeNamespace(@namespace);
            //生成客戶端代理類程式碼  
            CodeCompileUnit ccu = new CodeCompileUnit();
            ccu.Namespaces.Add(cn);
            sdi.Import(cn, ccu);
            CSharpCodeProvider csc = new CSharpCodeProvider();
            ICodeCompiler icc = csc.CreateCompiler();
            //設定編譯器的引數  
            CompilerParameters cplist = new CompilerParameters();
            cplist.GenerateExecutable = false;
            cplist.GenerateInMemory = true;
            cplist.ReferencedAssemblies.Add("System.dll");
            cplist.ReferencedAssemblies.Add("System.XML.dll");
            cplist.ReferencedAssemblies.Add("System.Web.Services.dll");
            cplist.ReferencedAssemblies.Add("System.Data.dll");
            //編譯代理類  
            CompilerResults cr = icc.CompileAssemblyFromDom(cplist, ccu);
            if (true == cr.Errors.HasErrors)
            {
                System.Text.StringBuilder sb = new StringBuilder();
                foreach (CompilerError ce in cr.Errors)
                {
                    sb.Append(ce.ToString());
                    sb.Append(System.Environment.NewLine);
                }
                throw new Exception(sb.ToString());
            }
            //生成代理例項,並呼叫方法  
            System.Reflection.Assembly assembly = cr.CompiledAssembly;
            Type t = assembly.GetType(@namespace + "." + classname, true, true);
            object obj = Activator.CreateInstance(t);
            System.Reflection.MethodInfo mi = t.GetMethod(methodname);
            return mi.Invoke(obj, args);
        }
        private static string GetClassName(string url)
        {
            string[] parts = url.Split('/');
            string[] pps = parts[parts.Length - 1].Split('.');
            return pps[0];
        }
    }
}

呼叫介面

            string surl = "http://localhost:41765/WebServiceDemo.asmx";
            string sclass = "";
            string sname = "TestWithParam";
            object[] args = { "動態呼叫WebService" };

            this.txtinfo.Text = WebServiceHelper.InvokeWebService(surl, sclass, sname, args).ToString();

方法二：

using System;
using System.CodeDom;
using System.CodeDom.Compiler;
using System.IO;
using System.Net;
using System.Text;
using System.Web;
using System.Web.Caching;
using System.Web.Services.Description;
using System.Xml.Serialization;

namespace WebServiceClient
{
    public class WebServiceHelper0
    {

        /// <summary>
        /// 生成dll檔案儲存到本地
        /// </summary>
        /// <param name="url">WebService地址</param>
        /// <param name="className">類名</param>
        /// <param name="methodName">方法名</param>
        /// <param name="filePath">儲存dll檔案的路徑</param>
        public static void CreateWebServiceDLL(string url, string className, string methodName, string filePath)
        {
            // 1. 使用 WebClient 下載 WSDL 資訊。
            WebClient web = new WebClient();
            Stream stream = web.OpenRead(url + "?WSDL");
            // 2. 建立和格式化 WSDL 文件。
            ServiceDescription description = ServiceDescription.Read(stream);
            //如果不存在就建立file資料夾
            if (Directory.Exists(filePath) == false)
            {
                Directory.CreateDirectory(filePath);
            }
            if (File.Exists(filePath + className + "_" + methodName + ".dll"))
            {
                //判斷快取是否過期
                var cachevalue = HttpRuntime.Cache.Get(className + "_" + methodName);
                if (cachevalue == null)
                {
                    //快取過期刪除dll
                    File.Delete(filePath + className + "_" + methodName + ".dll");
                }
                else
                {
                    // 如果快取沒有過期直接返回
                    return;
                }
            }
            // 3. 建立客戶端代理代理類。
            ServiceDescriptionImporter importer = new ServiceDescriptionImporter();
            // 指定訪問協議。
            importer.ProtocolName = "Soap";
            // 生成客戶端代理。
            importer.Style = ServiceDescriptionImportStyle.Client;
            importer.CodeGenerationOptions = CodeGenerationOptions.GenerateProperties | CodeGenerationOptions.GenerateNewAsync;
            // 新增 WSDL 文件。
            importer.AddServiceDescription(description, null, null);
            // 4. 使用 CodeDom 編譯客戶端代理類。
            // 為代理類新增名稱空間，預設為全域性空間。
            CodeNamespace nmspace = new CodeNamespace();
            CodeCompileUnit unit = new CodeCompileUnit();
            unit.Namespaces.Add(nmspace);
            ServiceDescriptionImportWarnings warning = importer.Import(nmspace, unit);
            CodeDomProvider provider = CodeDomProvider.CreateProvider("CSharp");
            CompilerParameters parameter = new CompilerParameters();
            parameter.GenerateExecutable = false;
            // 可以指定你所需的任何檔名。
            parameter.OutputAssembly = filePath + className + "_" + methodName + ".dll";
            parameter.ReferencedAssemblies.Add("System.dll");
            parameter.ReferencedAssemblies.Add("System.XML.dll");
            parameter.ReferencedAssemblies.Add("System.Web.Services.dll");
            parameter.ReferencedAssemblies.Add("System.Data.dll");
            // 生成dll檔案，並會把WebService資訊寫入到dll裡面
            CompilerResults result = provider.CompileAssemblyFromDom(parameter, unit);
            if (result.Errors.HasErrors)
            {
                // 顯示編譯錯誤資訊
                System.Text.StringBuilder sb = new StringBuilder();
                foreach (CompilerError ce in result.Errors)
                {
                    sb.Append(ce.ToString());
                    sb.Append(System.Environment.NewLine);
                }
                throw new Exception(sb.ToString());
            }
            //記錄快取
            var objCache = HttpRuntime.Cache;
            // 快取資訊寫入dll檔案
            objCache.Insert(className + "_" + methodName, "1", null, DateTime.Now.AddMinutes(5), TimeSpan.Zero, CacheItemPriority.High, null);
        }
    }

}

介面呼叫

配置檔案

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
    <!--WebService地址-->
    <add key="WebServiceAddress" value="http://localhost:41765/WebServiceDemo.asmx"/>
    <!--WebService提供的類名-->
    <add key="ClassName" value="WebServiceDemo"/>
    <!--WebService方法名-->
    <add key="MethodName" value="TestWithParam"/>
    <!--存放dll檔案的地址-->
    <add key="FilePath" value="D:\\測試Demo\\WebService"/>
  </appSettings>
</configuration>

            // 讀取配置檔案，獲取配置資訊
            string url = ConfigurationManager.AppSettings["WebServiceAddress"];
            string className = ConfigurationManager.AppSettings["ClassName"];
            string methodName = ConfigurationManager.AppSettings["MethodName"];
            string filePath = ConfigurationManager.AppSettings["FilePath"];
            // 呼叫WebServiceHelper
            WebServiceHelper0.CreateWebServiceDLL(url, className, methodName, filePath);
            // 讀取dll內容
            byte[] filedata = File.ReadAllBytes(filePath + className + "_" + methodName + ".dll");
            // 載入程式集資訊
            Assembly asm = Assembly.Load(filedata);
            Type t = asm.GetType(className);
            // 建立例項
            object o = Activator.CreateInstance(t);
            MethodInfo method = t.GetMethod(methodName);
            // 引數
            object[] args = { "動態呼叫WebService" };
            // 呼叫訪問，獲取方法返回值
            string value = method.Invoke(o, args).ToString();
            //輸出返回值
            MessageBox.Show($"返回值:{value}");

demo下載地址：https://quqi.gblhgk.com/s/3942311/uB6laF2mD7PgrqYF