Abstract: In this paper, a highly loaded meridian acceleration fan was designed for automobile air conditioning, and the three-dimensional numerical simulation on fan was conducted with Star CCM+. The internal flow field of meridional acceleration vortex is analyzed in detail, and the important flow details and laws in the flow field of fan are then obtained. The effects of the blade outlet angles, blade number and blade tip clearance on the fan performance were investigated. Finally, the optimal scheme was selected to process a set of blower CNC samples for performance testing. The test results show that the model testing results accords with the simulation results well, and the performance of fan can satisfy the design requirements. Therefore, the numerical simulation analysis can guide the optimal design of the fan.