Abstract: In traditional 3D process design, building process models relies heavily on manual modeling, which brings problems like low efficiency and poor model consistency and limits overall quality and efficiency of process design. To solve this problem, this paper proposes an automatic generation method of process models based on feature association and intelligent reasoning. This method builds a full process knowledge chain via feature recognition, machining reasoning and intelligent process sequence planning, and realizes one-click generation and update of process models. The system supports automatic PMI annotation, intelligent association of process resources and parameters, and structured input of process descriptions, cutting manual errors effectively. This paper elaborates the business logic, technical framework, core algorithms and implementation steps of the proposed method. Engineering cases verify that this method can boost design efficiency and ensure model consistency. It offers a feasible technical route for intelligent upgrading of 3D structured process design and valuable references for digital transformation of process design.