In this paper we propose methodologies and algorithms of NC cutter path generation for subdivision surfaces. We select Loop surface as the subdivision surface. A path plan including rough cut and finish-cut is developed based on LoD (Level of Detail) property of the subdivision surface. We generate a coarse mesh that covers the limit surface to implement rough cut. For finish-cut we use ball-end mills and offset cutter contact positions to generate cutter location. In these two steps we use a Z-map model and a collision detection and correction method is presented for the interference-free of these two steps. We implement our methods and present machining results. All of these two kinds of cutter paths are computed rapidly and automatically.