Abstract: To study the internal flow field distribution and pressure pulsation characteristics of a vehicle cam type hydrogen circulating pump under high speed operating conditions, a three-dimensional transient computational fluid dynamics model of a vehicle cam hydrogen circulating pump was established. The dynamic mesh technology based on ANSYS Fluent by using the Realizable k-ε turbulence model and the PISO pressure-velocity coupling algorithm were applied to perform unsteady compressible numerical simulation of the entire flow path of the hydrogen circulation pump. By setting pressure pulsation monitoring points in the circumferential direction of the rotating flow channel of the hydrogen circulation pump, and using fast Fourier transform（FFT） technology to obtain pressure pulsation frequency domain maps of each monitoring point, the pressure pulsation frequency distribution law in the flow channel was obtained. By comparing the numerical simulation results with the theoretical analysis results, it was verified that the numerical simulation method based on dynamic mesh technology could accurately predict the internal flow pulsation characteristics of vehicle cam hydrogen circulation pump. The research results show that the error between the average value of the exhaust gas flow obtained by the numerical simulation and the theoretical analysis result is 4.7%, which can accurately reflect the pulsation law of the gas flow in the pump. By analyzing the distribution of vorticity field in the exhaust passage, it is concluded that the outlet backflow in the exhaust passage is positively related to the negative z-direction vorticity. As the outflow gas occupying the exhaust passage, the negative z-direction vorticity disappears. The main frequency of circumferential pressure pulsation in the rotating flow passage of hydrogen circulation pump is 267 Hz, which is consistent with the fundamental frequency of the rotor rotation. The research results provide a reference for further analysis of the internal flow pulsation characteristics of the cam type hydrogen circulation pump.