Abstract: Lithium batteries are widely used in the field of new energy vehicles because of their high energy density, low self discharge rate and long cycle life. Due to the imperfection of lithium battery materials, production processes and other problems, it is easy to have potential safety hazards. This paper summarizes the factors that affect the safety performance of lithium batteries, expounds the defects of lithium batteries into three parts: surface defects, electrode defects and internal defects, introduces the types of defects and appropriate detection methods, and makes a summary comment on the integrated detection of the safety performance of lithium batteries.