This paper uses the ANSYS Fluent platform to perform simulation analysis and structural optimization of a lithium-ion battery pack in an energy storage system based on an electrochemical-thermal coupling model. First, a thermal simulation model of the battery is established. With it, the temperature distribution of the battery cell is obtained. The accuracy of the established simulation model is verified by comparison with the experimental measurement results. Then the simulation analysis of the air cooling system of the battery pack is carried out, and the solution of the temperature distribution of the battery pack and the flow velocity distribution of the air duct is completed. Finally, the cooling effect of the cooling system is improved by changing the number of air outlets and the shape of the fan baffle. The results show that it is feasible to analyze the temperature and internal flow velocity distribution of energy storage battery packs based on the electrochemical-thermal coupling simulation model. The structural optimization of the forced air cooling system can greatly improve the heat dissipation performance of the system, and achieve a lower maximum temperature and a more uniform temperature distribution. This work is supported by the Key Research and Development Program of Guangdong Province (No. 2020B090919004).