Abstract. Aiming at design efficiency and quality problems of NC program in multi-varieties and small-batch production mode, this paper applied the concept of product modular design into NC program design, and presented the modular design method of NC program and its implementation techniques. By design the module NC program structure and build the database of basic module, provided technical support for the modular design of NC program. The practical application shows those: the constructed module database can be reused and can be combined, using the modular design method can effectively improve the design efficiency and quality of NC program, especially for multi-varieties and small-batch parts, provides an optimal way for NC program to quickly meet the individual demands.