In this paper, an accurate SOC estimation method based on a robust H∞ filter is proposed, aiming at the problem that lithium-ion battery temperature affects model parameters, which leads to inaccurate SOC estimation,. Firstly, take the second-order Thevenin equivalent circuit model as the basic model of the lithium-ion battery. The influence of temperature on battery model parameters is modeled as an additive variable of the nominal resistance value and the total battery capacity, and the temperature change is regarded as an external disturbance of the system. After that, the sliding linear method is used to linearize its model; on this basis, a robust H∞ filter for SOC estimation is designed using linear matrix inequality technology. Finally, the pulse discharge current excitation and experimental data current excitation are used respectively, and the estimation result of SOC is compared with the estimation result of Kalman filter, which shows that the robust H∞ filter designed for SOC estimation can realize track SOC accurately, at the same time, it has good robustness to external disturbances.