An automatic set of pipe dust cap, characterized by including a pipe selector system, a pipe cap assembly system, and a control system. The pipe selector system comprises a frame and multiple selector disc wheels. The pipe cap assembly system is set on the side of the selector disc wheel mounted on the frame and includes multiple radial position limiting components for pipes and pipe cap assembly components. The pipe cap assembly components consist of a pipe cap component transmission mechanism and a pipe cap component positioning mechanism. The pipe selector system and the pipe cap assembly system are controlled by the control system. The selector disc wheels rotate the pipe to the position for fitting the pipe cap. The radial position limiting components for pipes limit the radial position of the pipe. The transmission mechanism and the positioning mechanism of the pipe cap components transmit and position the pipe cap for assembly with the pipe end.