/// <summary>
        /// WGS84經緯度轉Web墨卡托投影
        /// </summary>
        /// <param name="dLong">經度</param>
        /// <param name="dLat">緯度</param>
        /// <returns>返回包含坐標值的數組</returns>
        public static double[] WGS84ToMercator(double dLong, double dLat)
        {
            double[] BLtoXY = new double[2];
            double MercatorX = dLong * 20037508.34 / 180;
            double MercatorY = Math.Log(Math.Tan((90 + dLat) * Math.PI / 360)) / (Math.PI / 180);
            MercatorY = MercatorY * 20037508.34 / 180;
            BLtoXY[0] = MercatorX;
            BLtoXY[1] = MercatorY;
            return BLtoXY;
        }
 
        C#實現，實測還算精準，特此記錄。 

WGS-84經緯度轉Web墨卡托投影（C#版）