In order to reduce the flow resistance and improve the flow uniformity of the air filtration system of diesel engine locomotive, the CFD simulation method was used to analyze and study the hydrodynamics of the air filtration system of locomotive diesel engine in plateau environment. Firstly, the performance simulation calculation of air filter system of locomotive diesel engine at 0 m altitude is completed, and the structure of air filter system is optimized according to the calculation results. Then the optimized air filter system is calculated by CFD in plateau environment with altitude of 2200 m, 4000 m and 5100 m. Finally, the arrangement of the bag filter is studied. Based on the initial arrangement of the filter, the bag filter is rearranged into three kinds of arrangement of shun-66, cha-56 and cha-65, and the flow uniformity and turbulence performance of dif-ferent arrangement modes are studied. The results show that the cha-56 arrangement has the best turbulence performance and the smallest inlet resistance with the best flow uniformity.