The pressure water film copper mould tube is as follows: four steel plates are fixed at the lower end of the copper mould tube , water is sprayed from the slits processed on each steel plate, and the steel plate is placed in line with the copper mould tube surface, and left between the surface of the casting blank and the surface of the casting blank. With a small gap, the gap fills the high-speed flowing water and forms a water film. The slit on the steel plate is inclined downward so that the water flowing out therefrom can flow downward. The water film acts both as a strong cold and supports the slab. This is the pressure water film copper mould tube.