A power system of an electric vehicle, an electric vehicle including the same, and a method for heating a battery group of the electric vehicle are provided. The power system includes: a battery group; a battery heater connected with the battery group; a battery management device, configured to control the battery heater to heat the battery group when a temperature of the battery group is lower than a first heating threshold and a residual electric quantity of the battery group is larger than a running electric quantity threshold, to obtain a current throttle depth change rate of an electric vehicle in real time, and to control the battery heater to stop heating the battery group when the current throttle depth change rate reaches a preset throttle depth change rate threshold; an electric distribution box; a motor; a motor controller; and an isolation inductor.