public static Bitmap GetPieWithText(String text, Color color, Color fontColor,Font font)
{
    int size = 22;
    Bitmap bmp = new Bitmap(size, size);
    Graphics g = Graphics.FromImage(bmp);
    g.SmoothingMode = SmoothingMode.AntiAlias; //使繪圖質量最高，即消除鋸齒
    g.InterpolationMode = InterpolationMode.HighQualityBicubic;
    g.CompositingQuality 
 
= CompositingQuality.HighQuality;
    g.TextRenderingHint = TextRenderingHint.ClearTypeGridFit;
    g.FillPie(new SolidBrush(color), new Rectangle(0, 0, size-1, size - 1), 0, 360);
    g.SmoothingMode = SmoothingMode.Default;
    g.InterpolationMode = InterpolationMode.Default;
    g.CompositingQuality 
 
= CompositingQuality.Default;
    StringFormat stringFormat = new StringFormat();
    stringFormat.Alignment = StringAlignment.Center;
    if (text.ToString().Length == 2)
    {
        g.DrawString(text.ToString(), font, new SolidBrush(fontColor), new Rectangle(0, 0, size-1, size - 1), stringFormat);
    }
    
 
else
        g.DrawString(text.ToString(), font, new SolidBrush(fontColor), new Rectangle(0, 0, size - 1, size - 1), stringFormat);

    return bmp;
}

首先使用以上代碼解決，一直沒有解決問題，後來調整了繪制區區域大小size解決了問題，供大家參考。

C#一例繪制字體不清晰的解決辦法