Abstract: An experiment was carried out by differential measurement and backscattering mode. The Doppler signal was acquired by the data acquisition board PCI DAS-4020, and the signal data filtering was performed to improve SNR. The frequency spectrum was acquired by fast Fourier transform, and the calculated velocity of the moving target was compared with the actual velocity. The results show that the system is applicable for the velocity measurement of solid moving surfaces, and the accuracy can reach 2.2%.