The invention discloses a motion control interface and an interface controller of an open numerical control system. According to different process characteristics of an auxiliary process and a processing process, the motion control interface is divided into a non-real-time serial interface and a real-time linkage interface. The linkage interface solves the problem of real-time control of a cuttertrack curve by a simple technical means, and converts a real-time control process and a real-time communication process into a simplest real-time transmitting process of a linkage command. The linkage interface has an open real-time control process without a communication protocol and a communication cycle, so a complicated multi-axis synchronization driving technique is converted into a simple conventional technique. The linkage interface has remarkable advantages of simple system debugging and operational maintenance, complete openness to users, convenience for use, low price, capability ofbeing standardized and the like.