There is a need to better match the source and load of an off grid micro grid and reduce the disadvantages of over reliance on prediction information of energy management. Based on the research and engineering practice of the SOC state change trend of an energy storage battery, a control strategy based on expert rules is adopted for different operation modes and scenarios, and the micro grid energy management system is fully utilized. Integrated data acquisition and processing ensures that energy management can not only control the stable power of the microgrid according to the range of the SOC, but also according to the strategy table. In practical engineering application, the control network of power control is designed reasonably to ensure the rapidity and accuracy of control. The control method achieves the power automatic control of photovoltaic, wind power and a heat storage boiler, and improves the accuracy and robustness of the off grid micro grid steady-state source load balance control. This work is supported by National Major Special Project (No. 2018YFB0904800) and Strategic International Science and Technology Innovation Cooperation Key Project of National Key Research and Development Program of China (No. 2020YFE0200400).