System for preparing thin film, preparation method of thin film and thin film

The invention belongs to the technical field of film preparation. The invention discloses a system for preparing a thin film, which sequentially comprises an extrusion device, a longitudinal stretching device, a cooling device, a transverse stretching device and a heat setting device along the conveying direction of the thin film, in the conveying direction of the thin film, the cooling device sequentially comprises at least two shrinking rollers and at least two cooling rollers, the roller speed of the cooling rollers is smaller than that of the shrinking rollers, and the temperature of the cooling rollers is lower than that of the shrinking rollers. The invention further provides a preparation method of the thin film. The invention further provides a thin film. The thermal shrinkage rate of the film prepared by the system in the longitudinal stretching direction and the transverse stretching direction is small, so that the thermal shrinkage performance of the film is more stable, the service life of the fil