The software of Master CAM is popular in NC field.The approach that how to use Master CAM in NC machining was described from analyzing pars draft,designing entity models and confirming machining technics to producing and checking tools path,making practical NC code that have been post processed.With the help of Master CAM,manual programming is avoid,the efficiency of NC machining is higher,the machining precision is ensured and the quality of NC machining is higher.