The invention discloses a cooling device for a battery pack. The cooling device for the battery pack comprises a vehicle-mounted air conditioner. The vehicle-mounted air conditioner comprises an air conditioner controller which is respectively connected with an air conditioner panel, a compressor, a condensing fan and an air blower. The air blower comprises an air blower motor and an air door adjusting motor; an air blowing opening of the air door adjusting motor is respectively communicated with the battery pack and an in-vehicle space; a battery box and a temperature sensor are arranged inside the battery pack, and the temperature sensor is electrically connected with a battery heat management system of the battery box; and the battery heat management system is electrically connected with the air conditioner controller. The cooling device provided by the invention has the beneficial effects that by using the vehicle-mounted air conditioner and allocating a working state. different refrigeration methods are used according to different temperature levels in the battery pack and the cooling device is not influenced by ambient temperature in use, so that the temperature of the power battery pack is effectively reduced, the unnecessary energy consumption of a battery is avoided, the maximum utilization ratio of electric energy is reached, and the driving range of an electro-mobile is increased.