The development of battery technology is crucial for the development of EVs. This paper mainly introduces the technical development of lithium power battery. It includes the introductions on the safety technologies for single electric core unit and module and pack，including cathode and anode materials，electrolyte，and diaphragm etc.，the factors affecting the safety and solutions. In the area of module and PACK，we should implement multi-level protection，including the safety protection for module，system and use.