A small high speed centrifugal impellor had been modified by rearranging the blade thickness and meridian line type;then the improved impellor was simulated with Fine/Turbo software.The result shows that: the adiabatic efficiency of the improved impellor increases by 2.4% and it also has wilder surge margin.Besides
changing radial flow impellor to inclined flow impellor will comparatively decrease the separation of blades with sacrifice of the pressure ratio.