Numerical control last making machine is a machine that is used to process shoe last. A new principle of numerical control machining shoe last is put forward aiming at the deficiency of current carving last system. On the basis of the principle, the algorithm of cutter machining position during numerical controlled carving last is analyzed in detail. The complex problem of the calculation of cutter machining positiion is resolved by applying spherical milling cutter that is often used in machining free_curve surface today and taking account of practical situation of the shoe last_making machine. At the same time, the calculation of cutter machining position is realized by program using Visual C++6.0. As a result, the calculation time of cutter machining position is reduced greatly and the efficiency of design is improved. Moreover, the process of carving last is agile and precision of carving last is ensured.