IPolyline pl =  new PolylineClass();

 IPointCollection ptc = pl as IPointCollection;

 object missing = Type.Missing;

 for (int i = ; i < num1; i++)

 {

           IPoint pt = autoStation.GetFeature(i).Shape as IPoint;//提取点

           ptc.AddPoint(pt, missing, missing);

 }

 (pl as ITopologicalOperator).Simplify();

 IFeatureClass f1 = (ws as IFeatureWorkspace).OpenFeatureClass("bb1");

 IFeature fea=f1.CreateFeature();

 fea.Shape = pl;

 fea.Store();