The invention discloses a supported copper-based catalyst preparation method and applications of the supported copper-based catalyst in synthesis of ethylene glycol. The method comprises: taking a silicon mesoporous molecular sieve, carrying out a reaction with sulfonic acid, carrying out a hydroxyl condensation reaction with a silane coupling agent, carrying out a graft copolymerization reactionon the obtained modified silicon mesoporous molecular sieve, an initiator and an acrylic acid compound, adding the obtained solid sample into an ethanol/aqueous solution mixed solvent of a soluble copper salt, carrying out a heating reflux reaction, filtering the obtained product, repeatedly washing with deionized water, drying, and roasting to obtain the modified silicon mesoporous molecular sieve supported copper-based catalyst. According to the invention, with the preparation method, the dispersity of the copper species in the final catalyst can be regulated, and the synergistic effect of monovalent copper and zero-valent copper can be improved, so that the high-dispersion supported nanometer copper catalyst is obtained; with the application of the catalyst in a reaction for synthesizing ethylene glycol through hydrogenating dimethyl oxalate, the conversion rate of dimethyl oxalate is more than 99.4%, and the selectivity of ethylene glycol is more than 96%; and the preparation process of the catalyst is simple, the cost is low, and the industrial application is easily achieved.