Surface pitting will change the response characteristic of gear systems. Therefore, it is of great significance to study the vibration response of tooth pitting fault. In this article, the pitting model of the probability distribution on the tooth surface is established. Firstly, time-varying meshing stiffness (TVMS) is calculated. Secondly, the three-dimensional morphology of the tooth surface is constructed according to the established pitting model, and then the influence of surface pitting on tooth roughness and friction coefficient is analyzed. Subsequently, the dynamic model of gear systems is built based on lumped parameter method, and then the vibration response of the system is obtained. Results indicate that the tooth surface pitting reduces TVMS while increasing roughness and friction coefficient, thus improving vibration response. Meanwhile, the vibration response signal is affected by surface pitting, with a series of sidebands emerging in the signal spectrum.