private void changeRefrence(ISpatialReference isr){

    //新建中心点
    IPoint pPoint = new Point();
    pPoint.setX(X);
    pPoint.setY(Y);	
    pPoint.setSpatialReferenceByRef(igcs);

    //新建坐标系
    ISpatialReferenceFactory factory = new SpatialReferenceEnvironment();
    IGeographicCoordinateSystem igcs = factory.createGeographicCoordinateSystem(esriSRGeoCSType.esriSRGeoCS_WGS1984);

   //坐标转换 isr为目标坐标系
   pPoint.project(isr);

}