The invention provides a plastic sealing device for steel-framed enhanced polyethylene composite pipe ends. The plastic sealing device comprises a support and an injection molding device arranged on apanel of the top of the support. The injection molding device is composed of two transversely and symmetrically arranged half molds and a longitudinally arranged cylindrical core mold. Plastic molding mold cavities are formed in a corresponding manner in opposite sides of the two half molds. Pressing cylinders are arranged on rear sides of the two half molds respectively. The pressing cylinder bodies are fixed to the panel of the top. The half molds are fixed to ends of telescopic rods of the pressing cylinders. The core mold is fixed a telescopic rod of a telescopic cylinder. The core mold is matched with enclosing grooves at rear ends of the half molds. A plastic sprayer is arranged on a side wall of the back segment portion of the core mold. A heater for conducting heating melting on plastic at pipeline ends is arranged in the front segment portion of the core mold. According to the plastic sealing device for the steel-framed enhanced polyethylene composite pipe ends, the heating melting heater for plastic at the pipeline ends is arranged inside; moreover, a sealed injection molding manner is adopted so that high-pressure injection molding can be conducted at the pipeline ends;and the plastic sealing device has the advantages of being high in strength of plastic-sealed ends and beautiful in appearance.