Heat-resistant polyethylene copolymer preparation method, heat-resistant polyethylene copolymer and pipe

The invention discloses a heat-resistant polyethylene copolymer preparation method, a heat-resistant polyethylene copolymer and a pipe. According to the heat-resistant polyethylene copolymer preparation method, the steps that a magnesium chloride loaded TiCl4 Ziegler-Natta catalyst serves as a main catalyst, aluminum alkyl serves as an auxiliary catalyst, ethylene and alpha-olefin are catalyzed for copolymerization in an inert hydrocarbon solvent, and ethylene homopolymerization and copolymerization reaction of ethylene and alpha-olefin are conducted stage by stage through two serial connected reaction kettles; by changing the technological conditions of polymerization reaction, the polyethylene copolymer with good heat resistance can be obtained, and the copolymer can be extruded and formed easily to serve as a heat-resistant pipe material.