Dynamic response characteristic is important message to the diagnosis of gear with early surface spalling. However, the complexity of the contacting deformation in spalling area and coupling of the response signals result in difficulty to diagnosis of early gear fault. The dynamic model with surface spalling based on time-varying stiffness with edge contact is built to realize the response characteristic mechanism in spalling area and the new time-varying meshing stiffness algorithm with the multiplex contact stiffness algorithm of surface spalling fault is also established. The time-varying stiffness and system dynamic response with edge contact is analyzed. And researches on the mutation characteristic of edge contact at surface spalling boundary and the dynamic response characteristic are carried on with time- and frequency-domain methods. In addition, experimental investigation on the dynamic features of spalling fault is performed to validate the proposed theoretical method. It’s proved by simulation and experimental results that the meshing stiffness with surface spalling and its effect on dynamic response characteristic can be investigated precisely with the dynamic model with gear surface spalling, which could supply the monitoring to gear system condition with important reference value.