Analysis of dynamic characteristics of the defective bearing is significant for the fault diagnosis of the machinery. At present, there are few researches on numerical modeling of bearing with defective roller. To solve this problem, explicit finite element method is adopted in this paper to establish a nonlinear dynamic model of the cylindrical roller bearing with roller spalling defects. In the proposed model, the flexibility of all the components, the internal friction, the relative sliding, the finite size of the roller and the rollers-to-cage contact force are all considered. Then the proposed dynamic model is verified theoretically and experimentally. The vibration responses of bearing and the sliding behavior of defective roller and cage are analyzed based on the proposed numerical model. The results show that the roller-to-cage contact force will be increased and the slippage of the defective roller will be aggravated when the roller defect occurs. In addition, the increment of defect width and number of defective rollers will aggravate the vibration of bearing and the sliding of cage.