The invention provides a belt lifting device of industrial fiber packaging machinery. The belt lifting device is mainly used for transferring welding points of eight PET packaging belts during package compression, the eight welding points are transferred from a vertical surface of a compression bag to a compression seam of a horizontal surface of the compression bag, so that the welding points of the PET belts are prevented from being easily rubbed and touched by other objects in the transportation process, the breakage phenomenon of an industrial fiber bag in the transportation process is reduced, and the transportation safety is ensured. According to the welding point transferring process, belt pressing rotating blocks and belt pressing wheels are used for clamping the eight belts firstly, a motor is started after the eight belts are welded, a belt lifting sliding block is driven to slide on a guide rail to a certain position at the upper part of the guide rail through a transmission wheel, a transmission shaft, a transmission belt and the like, and then the belt lifting operation is completed for the first time. Then, the belt pressing rotating blocks are loosened, start sliding down and re-clamp the belt lifting device after the belt lifting device descends to the lower part, and then the belt lifting operation is carried out for the second time. According to the belt lifting device, different belt lifting frequency can be set according to the size of the fiber bag.