The present invention relates to the field of polymerization reactions, and discloses an ethylene polymerization method and polyethylene prepared through the method. According to the method, under a polymerization reaction condition, ethylene is subjected to a polymerization reaction in the presence of a catalyst, wherein the catalyst contains a spherical small-particle size mesoporous composite material and a magnesium salt and/or a titanium salt supported on the spherical small-particle size mesoporous composite material, and the spherical small-particle size mesoporous composite material contains a mesoporous molecular sieve material with a three-dimensional cubic cage-like pore channel structure. According to the present invention, the method uses the supported catalyst with the stablemesoporous structure, such that the polyethylene product with characteristics of low bulk density, low melt index and breaking resistance can be obtained.