The utility model discloses a cooling device of injection molding machine mould, including cold water machine, filter, booster pump, air -vent valve, the delivery port of cold water machine connect gradually filter and booster pump through the pipeline, be equipped with an air -vent valve on the booster pump, the delivery port of booster pump passes through the water inlet of pipe connection injection mold's cooling water course, the delivery port of injection mold's cooling water course is connected to the water inlet of cold water machine. Because the utility model discloses set up an air -vent valve and filter, the pressure of rivers in the adjustable entering of the air -vent valve injection mold, impurity in the filterable rivers of filter, the water route is difficult to be stopped up, and the water of cold water machine output is cold water, and the cooling effect is better for injection moulding product's quality obtains further assurance.