Focusing on the severity of asphalt pavement surface crack, a finite element analysis model of 20-node isoparametric elements was established by the commerce FEM software ABAQUS with the base of fracture mechanics theory. The surface crack of pavement was numerical analyzed and the crack propagation life was evaluated by Paris formula. In the course of surface crack propagation the change of the stress intensity factor (K2) was discussed and the effect of pavement parameters on surface crack fatigue life was studied. The analysis indicates: (1) the propagation of surface crack is dominated by deflection load. In the course of crack propagation, at first K2 increases to the top then drops down slowly. (2) the important influence factors to the surface crack propagation life at the scope of road structure parameter, are thickness and modulus of surface course, the modulus of base course. But modulus of subgrade, thickness and modulus of subbase course and thickness of base course are of no effect.