The state of charge (SOC) estimation accuracy for the lithiumion battery depends heavily on the battery model. Therefore, a combined model (Shepherdbased combined model, SCM) based on the improved Shepherd model coupled with temperature and cycle numbers is proposed. The thermal modeling and cyclic loss modeling of parameters, such as open circuit voltage, polarization constant, available capacity, and internal resistance in the Shepherd model, are considered in this paper. The identification method for model parameters is simplified to a nonlinear least squares method that only requires two sets of discharge experimental data at different temperatures. The discharge experiment is implemented by using lithiumion batteries of different cycle numbers and the actual working conditions of the electric vehicle are simulated by setting the lithiumion battery at different temperatures. The SOC dynamic estimations of SCM model and ECM model are implemented by using the extended Kalman filter algorithm. Simulation and experimental results show that the relative error of the proposed model is less than 15% and the SOC estimation error is less than 3%. The superiority of the proposed model is verified.