The invention relates to a cooling device of a packaging film production line. The cooling device comprises a conveying belt, a film extruding device, the production line, an air opening, a motor, an air inlet pipe, an air pump, a switch and a machine body. The conveying belt is arranged at the left end of the machine body. The film extruding device is arranged between the production line and the conveying belt. A square hole for containing the air opening is formed in the upper end face of the machine body. A round hole communicating with the air inlet pipe is formed in the bottom of the air opening. One end of the air inlet pipe is connected with the air opening, and the other end of the air inlet pipe is connected with the air pump. The switch is arranged on the left side of the air pump. The cooling device is novel and unique; with the help of the design structure of the cooling device, the use requirement of the cooling device is met well; the problems that on an existing packaging film production line, although the use requirement of the existing packaging film production line can be met, films cannot be cooled fast, films on a film winding shaft are prone to adhering to each other, and the quality of the films is reduced are solved; the film production quality is improved; and consumed cost is reduced.