Ball penetration test is used to measure the penetration depth of steel ball on the original asphalt pavement which is under impact load. The penetration depth is to evaluate the flexibility of the original pavement and one of mix proportion design parameters of chip seal. The test result is the plastic deformation of asphalt pavement under impact load. In this paper, layered half-space elastic-plastic model of the asphalt pavement is set up by transient dynamic analysis which is in structural analysis, the progress of the steel ball impacting pavement is numerical simulated, and the plastic deformation of asphalt pavement under impact load is studied. Results indicated that the using material parameters are mainly reasonable and the theoretical calculation result satisfies the requests of the engineering application. The method and results can be used in the theoretical analysis of chip seal mix proportion design.