The invention provides a testing method and device for specific heat capacity of a power battery. The method comprises the following steps: testing the specific heat capacity of the power battery by calibrating heat waste and heating and temperature equalization testing; acquiring a temperature-time changing curve of the power battery by calibrating the heat loss; keeping the constant temperatureof a cavity of a temperature control box unchanged, heating the power battery for a while with a film heater, then stopping heating, wherein the power battery is automatically dissipated and equalizedfor a preset time till the temperature of the battery power is uniform, and acquiring the average temperature rise; calculating the heat loss of the power battery according to the temperature-time changing curve; and calculating the specific heat capacity based on energy conservation. The specific heat capacity testing device of the power battery is simple, short in measuring time, accurate in testing result, low in cost and easy to operate, and can test the specific heat capacity of the power battery at different working condition temperatures.