Abstract: A 3-D C-H grid generation technique and 3-D Euler governing equation are described briefly.The highly loaded transonic compressor rotor designed by ONERA is taken as a numerical example.ONERA′S numerical results and ours with H grid and C-H grid are compared respectively in respect of the pressure distributions along profiles at hub and tip of the rotor.The numerical technique presented is applied to evaluating the influence of inlet pre swirl on its downstream flow field in the rotor,in result a new numerical approach is obtained for design optimization of pre swirl distribution at compressor design stage.As numerical examples,two kinds of pre swirl distributions are examined to show its influence on M_w1 、β₁ and α₂ etc. distributions along radius.