Disclosed is a traction battery self-heating control method and a device. Acquiring a second temperature of a rotor at a current sampling time according to system parameters and a first temperature of the rotor at a previous sampling time, and estimating a third temperature of the rotor at a next sampling time according to the first temperature and the second temperature, and stopping the self-heating of the traction battery when the third temperature reaches a demagnetization temperature of the rotor. Whether to stop the self-heating of the traction battery is determined by estimating a rotor temperature under the self-heating condition, and comparing the rotor temperature with the demagnetization temperature of the rotor, and thus the self-heating control of the traction battery is realized.