Abstract: Lithium battery energy storage is widely used in power system. Catastrophes such as fire or explosion of energy storage power station caused by lithium battery often occur. The fire safety research of lithium battery energy storage system has been seeking new breakthroughs. This paper introduces the technology of fire protection of lithium battery at present stage, and analyzes its deficiency and harm. At the same time, the reason and basic principle of the thermal runaway of the lithium battery energy storage system were studied. Aiming at the particularity of lithium battery energy storage fire protection, an efficient liquid nitrogen fire protection system and its control technology are designed. In this paper, a fire extinguishing test chamber based on liquid nitrogen fire fighting system is designed. The experiment verifies the fire extinguishing effect of liquid nitrogen fire fighting under the condition of lithium battery overcharge combustion, and proves the safety and efficiency of its application in lithium battery energy storage fire extinguishing.