The invention discloses a plastic pipe fitting. The plastic pipe fitting comprises an outer pipe, a left inner pipe, a left seal ring, a clamping pusher, a left inner pipe and a right seal ring. A table shoulder is arranged in the outer pipe, a zigzag structure is arranged on the inner wall of the right side of the outer pipe, the left inner pipe is installed in the outer pipe, an inner ring of the left seal ring is installed on the outer cylindrical surface of the left inner pipe, an outer ring of the left seal ring is installed on the table shoulder in the outer pipe, a left groove is formed in the position, close to the outer cylindrical surface of the right side, of the left inner pipe and is of an annular structure, a right groove is formed in the position, close to the outer cylindrical surface of the left side, of the right inner pipe and is of an annular structure, the right inner pipe is fixed and installed with the left inner pipe through the clamping pusher, and the right seal ring is installed between the clamping pusher and the left inner pipe and the right inner pipe.