/// <summary>
        /// MaplexEngine標註
        /// </summary>
        /// <param name="pGeoFeatLyr">標註圖層</param>
        /// <param name="pMap">地球人都知</param>
        /// <param name="annoField">標記字段</param>
         public void Annotation(IGeoFeatureLayer pGeoFeatLyr, IMap pMap, string
 
 annoField)
        {
            IAnnotateMap pAnnoMap;
            pAnnoMap = new MaplexAnnotateMapClass();
            pMap.AnnotationEngine = pAnnoMap;
            IGeoFeatureLayer pGeoFeatLayer;
            pGeoFeatLayer = pGeoFeatLyr;
            IAnnotateLayerPropertiesCollection pAnnoProps;
            pAnnoProps 
 
= pGeoFeatLyr.AnnotationProperties;
            pAnnoProps.Clear();
            ILabelEngineLayerProperties2 pLabelEngine2 = new MaplexLabelEngineLayerPropertiesClass();
            pLabelEngine2.Expression = "[" + annoField + "]";
           
            IMaplexOverposterLayerProperties pMaplexPro 
 
= new MaplexOverposterLayerPropertiesClass();
            pMaplexPro.FeatureType = esriBasicOverposterFeatureType.esriOverposterPolygon;
            pMaplexPro.PolygonPlacementMethod = esriMaplexPolygonPlacementMethod.esriMaplexHorizontalInPolygon;
            pMaplexPro.CanPlaceLabelOutsidePolygon = false;
            pMaplexPro.CanRemoveOverlappingLabel = false;
            pMaplexPro.RepeatLabel = false;
            pLabelEngine2.OverposterLayerProperties = pMaplexPro as IOverposterLayerProperties;
            IMapOverposter pMapPos = axMapControl1.Map as IMapOverposter;
            IOverposterProperties pOP = pMapPos.OverposterProperties;
            IMaplexOverposterProperties pMaplexOP = pOP as IMaplexOverposterProperties;
            pMaplexOP.LabelLargestPolygon = false;
            pAnnoProps.Add(pLabelEngine2 as IAnnotateLayerProperties);
            pGeoFeatLyr.DisplayAnnotation = true;
        }

來自：https://www.cnblogs.com/cannel/archive/2011/03/24/1993383.html

IAnnotateMap pAnnoMap = new MaplexAnnotateMapClass();
m_hookHelper.FocusMap.AnnotationEngine = pAnnoMap;

使用Maplex

ArcGIS Engine Maplex Label（標註）使用一例（轉)