The invention discloses an all-plastic straight-cutting structure pipe fitting. The all-plastic straight-cutting structure pipe fitting comprises a pipe fitting body, a seal ring, a plastic locking ring and a cover. The pipe fitting body is provided with a through water pipe by injection molding. A groove is provided between the inner wall of the pipe fitting body and the through water pipe. The groove is inserted with the seal ring. Both ends of the ouer wall of the pipe fitting body are threaded sections. The base of the plastic locking ring is tightly connected with the groove. The inner wall of the extension end of the plastic locking ring is provided with a fishhook-shaped pawl. An opening channel is provided between the inner wall of the plastic locking ring and the through water pipe. The fishhook-shaped pawl is used for embracing hoop and clamping the inserted pipeline. The cover is connected to the pipe fitting body in a screw thread mode. The inner side of the cover is axially provided with a threaded hole and an arc pressurized surface. When the cover is screwed into the pipe fitting body, the plastic locking ring is gradually pressurized by the arc pressurized surface.By the above-mentioned manner, the all-plastic straight-cutting structure pipe fitting is simple in structure, is made of all plastic, does not have any metal parts, is low in cost, is connected in astraight cutting manner, is convenient and efficient, saves a lot of labor cost, and is convenient for installation, disassembly and use.