Abstract: Under the condition of cold temperature, the charge-discharge performance of batteries in electric vehicles is dropped substantially due to the increase of viscosity of battery's electrolyte and the ascent of internal resistance. The method and development of heating battery system becomes a key technique to be solved. This research has developed a wide-line metal film method for heating batteries and performed low-temperature charging and discharging experiments on 80 A·h Li-ion battery cell. A model of heating battery was built and its correctness was verified by heating experiments with equivalent battery. Heating and discharging experiments of battery cell at -40 ℃ were implemented, and the results show that the discharge performance of heated battery cell is significantly improved.