In order to study the influence of the random dynamic load of vehicles on the performance of half rigid asphalt road, the driving dynamic model of heavy truck was established by SIMPACK and each dynamic normal tyre force was extracted. A 3-D finite element analysis (FEA) model of half rigid asphalt road was established, and the dynamic responses of half rigid asphalt road under random dynamic load was analyzed. The results showed that the stress change of half rigid road was relative to the number of axles. When the wheels of a triaxial vehicle ran over the road in turn, the stress of each layer changed abruptly three times, and the maximal stress appeared when the middle axle and rear axle ran over. Within the vehicle driving region, the maximal press and tensile stress of each point on the pavement varied with the changes of driving distance and dynamic normal tyre force. The varied frequencies of the vertical stress, horizontal stress, transverse stress and horizontal shear stress of the points on the central line of the wheel track were similar to the varied frequency of the dynamic normal tyre force of middle and rear axles; and the varied frequency of transverse shearing stress were similar to the dynamic normal tyre force of front axle. However, the varied frequency of transverse shear stress of the points on the edge of wheel track was similar to the dynamic normal tyre force of middle and rear axles.