The 3D model of inlet switch mechanism was established by Pro/E. At the same time, with the mechanism dynamics simulation module of Pro/E, the movements of inlet switch mechanism was simulated and verified. At last, the numerical simulation and analysis for air flow in the anti-drainback valve shell was made by CFD software Fluent. This method can be used to forecast and validate the design quality and assembly, and could be applied in the selection and optimizing design of inlet switch mechanism of sequential turbocharging system.