To solve the difficulties in modeling, designing, and simulation analysis of helical gear in high-pressure equipment, a parametric method for modeling and simulation of helical gear is proposed, and a user-oriented CAD-FEM coupled modeling and simulation analysis system is designed and developed. The geometry equation and data structure are used to describe the state of the modified helical gear model, the point, and line, and surface feature structures are established by the parametric design method, the integrated software platform for modeling, and grid division. Simulation analysis of the modified helical gear is established, the model data and its affiliated structures are shared, and the CAD-FEM module coupling is realized. The platform has the advantages of strong interactivity, good stability, high modeling and simulation analysis efficiency, small data volume, etc. Direct modeling and simulation analysis without data reconstruction and conversion provides a parametric method and software platform for modeling, design, and simulation analysis of modified helical gear.