Based on the Partnership for a New Generation of Vehicle (PNGV) model, the internal state variables of the battery are estimated based on the measured external variables. The experiment uses hybrid pulse power characterization (HPPC) method to obtain the lithium battery in the pulse loading and the transition process parameters. Finally, the PNGV equivalent model of the battery is simulated and analyzed by MATLAB/Simulink. The results show that the selected PNGV model has high precision and can simulate the charge and discharge characteristics of battery truly. The model parameters can be estimated accurately under fixed temperature and known SOC. The experimental results can provide a theoretical basis for internal state variable estimation of lithium batteries.