Abstract: Three kinds of centrifugal compressor impellers having straight-line element, positive and negative bowed blades were designed applying computer-aided integrated design system. Flow fields of serial impellers with different bowed blades were calculated by solving three-dimensional Navier-Stokes equations. The results of calculation are given. Entropy distribution on the blade pressure and suction surface having 1.5 mm curving degree at the middle span about positive and negative bowed blades were compared. Calculation results illustrated that the impeller adiabatic efficiencies of inlet positive bowed blades are higher than those of inlet negative bowed blades. The impeller adiabatic efficiencies of outlet positive bowed blades are nearly the same as those of outlet negative bowed blades. Different degrees of curvature in small centrifugal compressors have little effect on the impeller adiabatic efficiency.