Abstract: To study the characteristics of Li-ion battery and evaluate its usability on electric vehicles (EV), detailed examinations about the performance of Li-ion battery are carried out. On the base of these examinations the charging and discharging curves of Li-ion battery under different conditions are drawn, and various parameters are derived. Characteristics of Li-ion battery are analyzed, the influencing factors such as temperature and the charging and discharging rates are studied, and advises of guidance and operational suggestions for the battery in low temperature use are put forward.