Abstract: WJ5A compressor has been modified.The performance data obtained in testing prior to and after the modification of the compressor are compared.Test results indicate that the performance of the modified compressor is greatly improved.In the case of the relative corrected speed η_np1 =1.0,the maximum isentropic efficiency of the modified compressor ηkmax is increased by 3 6%.When η_np1 =0 70～0 90,η^*_kmaxis increased by over 15%.The pressure ratio and the mass flow are changed only a little at all speeds.When η_np1 >1 0,there is no evident variation in the compressor performance.