Mxd文件中加入多个地图

IMapDocument mapDocument = new MapDocument();
mapDocument.New(MxdPath); 
IGraphicsContainer pGraphicsContainer = mapDocument.PageLayout as IGraphicsContainer; 
for(int i = 0; i<3 ;i++)
{
    IMapFrame pMainMap = new MapFrameClass();
    IMap pMap = new MapClass();
    pMainMap.Map = pMap;
    pGraphicsContainer.AddElement(pMainMap as IElement, 0);
}
mapDocument.Save(true, true);
mapDocument.Close();