A power system of an electric vehicle, comprising: a battery group; a battery heater, connected with the battery group and configured to charge and discharge the battery group to heat the battery group; a battery management device, connected with the battery group and the battery heater respectively, and configured to control the battery heater to heat the battery group in a running heating mode or in a parking heating mode according to a temperature and a residual electric quantity of the battery group when the temperature of the battery group is lower than a first heating threshold and the residual electric quantity of the battery group is larger than a parking electric quantity threshold; an electric distribution box, configured to distribute a voltage output by the battery group; a motor; a motor controller, connected with the motor and the electric distribution box respectively, comprising a first input terminal, a second input terminal and a pre-charging capacitor connected between the first input terminal and the second input terminal, and configured to supply power to the motor according to a control command and a voltage distributed by the electric distribution box; and an isolation inductor, connected between the battery group and the electric distribution box, characterized in that the inductance L of the isolation inductor is determined according to the formula T = 2 ⁢ π LC, where T is an equivalent load work cycle of the motor, and C is the capacitance of the pre-charging capacitor; wherein the battery management device is configured to control the electric vehicle to enter the running heating mode when the temperature of the battery group is lower than the first heating threshold and the residual electric quantity of the battery group is larger than a running electric quantity threshold, in which the running electric quantity threshold is larger than the parking electric quantity threshold; wherein the battery management device is further configured to control the electric vehicle to enter the parking heating mode when the temperature of the battery group is lower than the first heating threshold and the residual electric quantity of the battery group is larger than the parking electric quantity threshold but lower than the running electric quantity threshold. a battery group; a battery heater, connected with the battery group and configured to charge and discharge the battery group to heat the battery group; a battery management device, connected with the battery group and the battery heater respectively, and configured to control the battery heater to heat the battery group in a running heating mode or in a parking heating mode according to a temperature and a residual electric quantity of the battery group when the temperature of the battery group is lower than a first heating threshold and the residual electric quantity of the battery group is larger than a parking electric quantity threshold; an electric distribution box, configured to distribute a voltage output by the battery group; a motor; a motor controller, connected with the motor and the electric distribution box respectively, comprising a first input terminal, a second input terminal and a pre-charging capacitor connected between the first input terminal and the second input terminal, and configured to supply power to the motor according to a control command and a voltage distributed by the electric distribution box; and an isolation inductor, connected between the battery group and the electric distribution box, characterized in that the inductance L of the isolation inductor is determined according to the formula T = 2 ⁢ π LC, where T is an equivalent load work cycle of the motor, and C is the capacitance of the pre-charging capacitor; wherein the battery management device is configured to control the electric vehicle to enter the running heating mode when the temperature of the battery group is lower than the first heating threshold and the residual electric quantity of the battery group is larger than a running electric quantity threshold, in which the running electric quantity threshold is larger than the parking electric quantity threshold; wherein the battery management device is further configured to control the electric vehicle to enter the parking heating mode when the temperature of the battery group is lower than the first heating threshold and the residual electric quantity of the battery group is larger than the parking electric quantity threshold but lower than the running electric quantity threshold.