In this paper, an integral model of the on-load tap changer transformer with solid-state switches is proposed and analyzed. Depending on the state of thyristors, the switching process of the model is divided into three stages, while the equations are unified in the same differential form. The parameter calculation of both single-phase transformer and tap changer are set up. Then, the simulation is performed based on the 4th-order Runge-Kutta algorithm, and the dynamic signals and the transient state are analyzed. Furthermore, the influence of circuit impedance on the signal waveform is discussed, followed by the study of the trigger time. The feasibility and rationality of the proposed model are validated by means of simulation tests, and it can be useful in the further parameter optimization and control strategy design.