An automatic set-up device for dustproof pipe caps for water pipes, characterized by comprising a tube feeding system, a pipe cap set-up system, and a control system. The tube feeding system includes a frame and multiple tube feeding wheel disks. The pipe cap set-up system is disposed on the side of the tube feeding wheel disks mounted on the frame and includes multiple radial positioning components for water pipes and pipe cap set-up components. The pipe cap set-up components consist of a cap component transmission mechanism and a cap component positioning mechanism. The tube feeding system and the pipe cap set-up system are controlled by the said control system. The tube feeding wheel disks rotate the water pipes to the position for fitting the pipe caps. The radial positioning components of the water pipes limit the radial position of the water pipes. The cap component transmission mechanism and the cap component positioning mechanism transmit and position the pipe caps for fitting with the ends of the water pipes.