Wheelset　driving　system　is　a　key　function　unit　of　CNC　underfloor　wheelset　lathe,　its　properties　and　accuracy　play　a　decisive　role　for　working　accuracy　of　the　wheelset　(trains,　subways　etc)　tread.　At　first,　it　analyses　the　force　of　cutting　point　for　wheelsets,　and　then,　contact　mechanics　analysis　and　delivering　power　analysis　are　established　based　on　friction　wheels　and　wheelsets＇　actual　contact　mechanics　equations　on　wheelset　driving　system　in　this　paper.　At　last,　in　order　to　analyze　wheelset　driving　system＇s　rigidity　and　degree　of　deformation　with　loading　condition,　modeling　analysis　and　static　force　analysis　are　set　up　in　the　finite　element　software　after　building　wheelset　driving　system＇s　three-dimensional　model.