Abstract: In this paper, the experimental surface roughness of pavementis regarded as the random input and the vehicle is simplified as a five degree-freedom system. The interaction force of Man-Vehicle-Road system is investigated by means of random vibration. The response spectrumand standard deviation of the force is calculated with different cases of pavement roughness. In the end of the paper, the compared results between theory and experiment show that the values of calculation and experiment are very similar.