Aiming at the problems of low utilization rate of angular box parts’ process information, and process design and numerical control programming depend on the repeated work of personnel and low efficiency, an automatic generating method of process model parameterization based on cutting body decomposition was proposed. The typical features of the parts were analyzed, and the principles of interference, non-interference, superposition and non-superposition were customized to classify the typical parts. The typical process model and the typical process of connecting the platform in the frame with four edges were constructed according to the machining requirements of parts. Based on the principle of volume decomposition, the cutting element body was constructed by using parameterizing negative entity. A parameterized model was built by using CATIA software in assembly mode, and its parameters were instantiated and verified. The results show that by using this method, the existing process information can be effectively reused, the parameter malformation caused by feature combination can be avoided, and the parameterization and instantiation of typical process model can be realized to improve the efficiency of process programming and NC programming.