The invention belongs to the field of coatings and particularly relates to a polyethylene powder coating used for an anti-corrosion steel pipe and a preparation method thereof. The polyethylene powder coating is characterized by comprising the following components in parts by weight: 100 parts of polyethylene resin, 2-4 parts of modified nanometer SiO2, 2-10 parts of antioxidant, 1-5 parts of light stabilizer, 5-10 parts of modifying agent, 0.1-0.5 part of flatting agent and 5-20 parts of pigment. In the polyethylene powder coating, the nanometer SiO2 is used for modifying the coating, and the adhesive force of the polyethylene powder coating and a metal matrix is improved. In order to realize the purpose that the nanometer SiO2 is stable and even in the matrix material, a silane couplingagent KH-550 adopted in the polyethylene powder coating is adopted for modifying the nanometer material. The powder coating disclosed by the invention has the advantages of good adhesiveness with metal steel, small possibility of cracking, good anticorrosive weathering resistance, long service life, smooth and flat coating film surface, good decoration effect, good mobility and wide market space,and is simple to construct.