The motion simulation system of underwater vehicle was developed based on dynamic model of the underwater vehicle and software platform - MultiGen Creator and Vega. The architecture of the simulation system was introduced. The coordinate system and 6-DOF dynamic equations of the underwater vehicle were constructed. The 3D modeling method based on Creator, the effect generation method of ocean environment and collision detecting method were discussed By using Vega to drive models, the visual simulation module was built. The simulation results show that this simulation system can realistically demonstrate the motion of underwater vehicle and satisfy the real time requirement. The system can also provide a platform for debugging and validating of the underwater vehiclepsilas intelligent control algorithm.