mini-Automatic Underwater Vehicle (mini-AUV), by the virtue of its advantages, has a promising future in the fields such as ocean science research, military application and commercial market. The research on mini-AUV hydrodynamic performance is the base of analysing the maneuverability and control method when the mini-AUV was working in complex oceanic environment also is the research focus. The hydrodynamic performance of a mini-AUV who had an axisymmetric body and four flat plate rudders on its tapered tail were calculated in this paper. The resistances and lateral forces of the mini-AUV at the incidence angles up to 10 degree were calculated based on the RANS equations. The simulations were verified with the grid quantities and turbulence models. The parallel processing was taken to accelerate the calculation; and the parallel speedup and efficiency were evaluated. The heave motions of the mini-AUV at different frequencies were simulated by dynamic mesh method under structure mesh. Overall the numerical results were validated from the experiments conducted in the circulating water channel. The numerical results proved the validity and practicability of solving this kind of issues by using this method, and give important reference for the mini-AUV's maneuverability design and analysis, motion simulation and control.