The invention discloses a thermal management system and a thermal management method of a vehicle battery pack, and relates to the technical field of vehicles. The thermal management system comprises an ambient temperature sensor, a battery temperature sensor, an electronic control unit and a water circulation channel, wherein the water circulation channel sequentially passes through an electronicwater pump, a battery pack, a heat dissipator and an air conditioner cooling device, and is used for conducting the heat generated by the battery pack, and when the temperature detected by the ambienttemperature sensor does not exceed a first threshold, and the temperature detected by the battery temperature sensor reaches a second threshold and does not exceed a third threshold, the heat dissipator and the air conditioner cooling device cool the battery pack. The invention further provides a corresponding thermal management method. According to the present invention, with the system and themethod, the continuous driving mileage of the vehicle battery pack can be lengthened, and the fuel consumption of the hybrid vehicle can be reduced so as to substantially improve the effects of energysaving and emission reducing.