With dynamic stress intensity factor (DSIF) as a characteristic parameter, this paper makes an analysis on the effect of parameters variation of vehicle speed, asphalt overlay thickness, modulus and old cement concrete pavement joint width on asphalt overlay reflective crack by investigating the variation law of reflective crack of asphalt overlay structure suffer wheel load. The results show that: the maximum dynamic stress intensity factor decreases with the increase of speed. Numerical value of maximum dynamic stress intensity factor is larger than the corresponding value of the static load. The longer the initial crack, the less the times of sustaining load of the same extending length. The increase of asphalt overlay thickness can reduce the value of dynamic stress intensity factor to a certain extent. With the augmentation of asphalt overlay modulus, the effect of dynamic load on reflective crack can be reduced in some degree. Dynamic stress intensity factor increases with the increase of joint width.