A battery management system (BMS) for energy storage power station is designed. Based on the topology of the BMS of energy storage power station and the characteristics of lithium batteries, a BMS with Freescale microcontroller unit (MCU) and ADI battery management chip(MC9S12 and LTC6811) as core devices is designed. BMS can realize the voltage and temperature collection and balanced control of the batteries of multiple circuits. Meanwhile, based on the sample data, the state of charge (SOC) of the battery can be calculated by utilizing the designed improved amperehour integration method. Based on the real data, the sampled values of battery voltage and temperature are compared with the real values, meanwhile the balanced effects and SOC are analyzed. Experimental results prove that the designed BMS has high sampling accuracy and sampling speed, and the balanced control is reasonable. The error of the estimated SOC value is small, indicating the practicability of the designed BMS.