To study the high frequency electromagnetic noise of the new energy electric vehicle during running, the noise, vibration and harshness (NVH) test and electromagnetic simulation analysis of some kind of new energy bus are carried out. Two-dimensional Fourier transform is made in the time domain and space domain on the solved electromagnetic force density, and it is determined that the electromagnetic noise is mainly caused by the 0 order 72nd harmonics according to the experimental data. The motor structural parameters of the motor rotor such as the angle between the magnetic steels, the length and width of the magnetic steel and so on, are taken as design variables to optimize the electromagnetic force density and torque ripple of the motor. Meanwhile, the multi-physics fields simulation of the electromagnetic field, structure and acoustics is made to solve the electromagnetic noise with the finite element method based on the optimized model, and the NVH tests of the vehicle are carried out to validate the simulation results. Test results show that the overall noise of the vehicle is reduced by 8.53 dB(A), the maximum noise of the 72nd harmonics of the motor is reduced by 18.59 dB(A), and the maximum 7th order noise of the gearbox is reduced by 5.02 dB(A). Simulation results are consistent with experimental test results.