The present invention provides a thermal management system of a power battery pack, including a heating branch, a cooling branch and a battery pack pipeline, the heating branch and the cooling branch are connected with the battery pack pipeline and are arranged in parallel and configured to enable switching, a first heat exchanger for absorbing heat from a cooling liquid pipe of an outer high-temperature device is arranged on the heating branch. The thermal management system of the battery pack provided by the present invention uses waste heat of the cooling liquid of other high-temperature devices on the electric vehicle to heat the battery pack, so as to avoid the problem of electric power consuming and cruising distance reduction. Meanwhile improving cooling efficiency of high-temperature devices, and then improve comprehensive energy utilization efficiency, and improve working condition of the whole vehicle, thereby improving comprehensive performance of the electric vehicle.