FCEV needs to cathode air to generate electricity through the fuel cell stack. To supply air to the feul cell stack is required high pressure ratio and the turbo blower of centrifugal compressor type is used. The performance of centrifugal compressor is most affected on impeller design. Thus this study shows the method of optimizing impeller shape for several design parameters using CFD and Taguchi method. Using CFD gives advantages to reduce cost and time making proto sample and to help understand flow mechanism over the impeller and turbo blower.