In order to understand the effects of different parts on the aerodynamic noise of the claw alternator for vehicle at high rotational speeds, the aerodynamic noise characteristics of the claw alternator were studied by numerical simulation. The no-load acoustic power level experiments of the claw alternator for vehicle were carried out to verify the accuracy of the numerical simulation. The noise sources of each order were determined by removing front fan or rear fan, or claw, and replacing claw with cylinder envelope. The contribution levels of front and rear fans and claw to noises at different orders were clarified. The results show that dipole was the main noise source at high rotational speed. The front fan mainly influenced the aerodynamic noise at 8th, 10th, 12th and 16th order. When the front fan was removed, the aerodynamic noise at 12th and 16th order was reduced by 6.54 dB(A) and 9.04 dB(A), respectively. The rear fan mainly affected the aerodynamic noise at 6th, 8th and 10th order. When the rear fan was removed, the aerodynamic noise at 6th, 8th and 10th order was reduced by 11.75 dB(A), 2.42 dB(A) and 7.38 dB(A), respectively. With or without claw had slight influence on the aerodynamic noise, but when the cylinder envelope was used to replace the claw, the flow field was affected, causing a certain change of the noise at the 8th order and also verifying that the front and rear fans were main sources of the aerodynamic noise.