Abstract: Automatic process model creation is the core function of the 3D part machining process planning system. In order to improve the speed and quality of three-dimensional process model modeling, this paper proposes an automatic modeling method based on the featured cutting body, which means the operation model of the current operation is “subtracted” from the previous operation model. Firstly the correlation is established between the process model and the process by using the machining features and machining feature work steps, and the feature cutting body is obtained by matching the machining features in the cutting body library. It instantiates the feature cutting body according to the dimensional and positioning parameters of the machining features, and determines its defining parameters and positioning parameters to finally form the cutting model; then does the Boolean subtraction operation between the previous process model and the feature cutting body model to obtain the process model of the current process. This approach takes machining features and feature cutting body as the core, blank model and process information as the basis, and margin size as the driver, and generates each process model according to the actual processing order in a forward direction. This forward process model generation method is consistent with the real part processing process, and after application verification in enterprises, it fully meets the enterprise application requirements, greatly reduces the workload of process personnel in the process model, so that they have more resource and time for improvement and innovation of the process. It also could be used in improving the process level and capability of Chinese manufacturing enterprises.