In the study, the shaping simulation of internal helical gears with crowned teeth is analyzed firstly. The shaper cutter and the generated gear are set up with non-parallel axes to achieve the tooth crowning effect. Applying visual basic and SolidWorks API, the gear shaping process can be simulated, and the 3D models of internal helical gears with crowned teeth can thus be obtained. Then, the contact patterns are simulated, and the contact stresses are analysed by commercial FEA package. The results of contact pattern simulation and stress analysis can be verified mutually.