In order to simplify the complexity of manually writing NC code and improve the processing efficiency, an automatic processing system for tenon based on image feature recognition was introduced. The key technologies such as the general structure of automatic NC processing based on image feature recognition, the establishment of model feature database, feature matching algorithm and processing technology database,were focused on. The main functions and implementation methods of the image feature library, NC database and image retrieval algorithm for the mortise model were analyzed in detail.