The surfaces of gear teeth are often subjected to spalling fault, which would deteriorate the functioning of gear transmission. In most of existing dynamic models of spalling gears, the load is treated as a constant while calculating the meshing stiffness. The resultant mesh stiffness thus the corresponding dynamic models are not able to truly reflect the meshing state of a gear pair as the load is varying during meshing process. To solve this problem, a new dynamic model of spalling gears is developed, wherein the meshing stiffness is calculated based on dynamic load. To be specific, the load change process of gear spalling meshing is expressed dynamically. The meshing stiffness is calculated through the coupling of dynamic load and dynamic model of gear. The numerical iterative method of Euler-Cromer was used to solve the dynamic equations of gear. The dynamic characteristics of the system were obtained when the spalling fault occurred. The comparison between the simulation results and the traditional spalling gear model shows that the proposed spalling gear model has a better accuracy.