Abstract: In order to solve the safety problem of thermal runaway propagation of batteries, a 230A·h square lithium iron phosphate battery was selected to experimentally study the thermal runaway behavior triggered by different heating powers. The results show that with the decrease of heating pad power, the temperature of the heating surface of the battery shows a downward trend, and the temperature of the heating surface is the lowest 248.9°C at 100W power, which can also be used to assist in the determination of whether the receiver battery has thermal runaway during the thermal safety design of the module. When the power of the heating pad decreases to 300W, 200W, and 100W, the growth of heat absorption gradually slows down, and the curve tends to flatten out. The research results have certain reference value and guiding significance for the safety design of lithium-ion battery modules and the suppression of thermal runaway.