//要加载的IFeatureClass

 IFeatureClass pFeatClass = dataset as IFeatureClass;

 //新建要加载到mxd文档中的图层

 IFeatureLayer pFeatLayer = new FeatureLayerClass();

 //设置新加图层的要素类

 pFeatLayer.FeatureClass = pFeatClass;

 //设置新家图层的名称

 pFeatLayer.Name = pFeatClass.AliasName;

 //GetRenderLayer函数实现从已配置好符号风格的mxd文档中的同名图层

 IGeoFeatureLayer pGeoLayer = GetRenderLayer(pFeatClass.AliasName) as IGeoFeatureLayer;

 //定义新加载图层为IGeoFeatureLayer类

 IGeoFeatureLayer pNewGeolayer = pFeatLayer as IGeoFeatureLayer;

 //为新加载图层设置符号风格

 pNewGeolayer.Renderer = pGeoLayer.Renderer;