Abstract: Lithium-ion battery is one of the core components of electric vehicles and energy storage systems, and it is crucial to explore the operation status of lithium batteries under different working conditions. Through the rate discharge experiment of lithium iron phosphate battery in a wide temperature range, the relationship between voltage, capacity and temperature of lithium battery is studied, so as to analyze the influence of discharge on the characteristics of lithium iron phosphate battery at different temperatures and different rates. The experimental results show that the voltage drop of the battery is obvious at-15-0 ℃ under the typical discharge rate of 1C, and the voltage drop decreases gradually with the increase of temperature, and the energy availability of the battery is less than the capacity availability at low temperature. In the same temperature range of high-rate discharge, the difference of the overall discharge capacity is small, all within 5%. At 35-60 ℃, the change trend of discharge curve at each rate is similar. The research results can provide a reference for the battery to find the appropriate operating conditions in practical applications, and have certain engineering application value.