The invention discloses an epoxy curing agent for concrete refinishing paint, and a preparation method and application of the epoxy curing agent. The preparation method of the epoxy curing agent includes 1), allowing a carboxylic phenolic compound to react with a mercaptan compound to obtain a sulfhydryl phenolic compound; 2), under the action of an acid catalyst, evenly mixing an amine compound,the sulfhydryl phenolic compound and an aldehyde compound to react to obtain sulfhydryl-terminated phenolic aldehyde amine; 3), injecting nitrogen into a mixture of a titanium dichloride compound andbenzene, slowly adding the sulfhydryl-terminated phenolic aldehyde amine after the pH value of a reaction system reaches 9-10, and performing distillation after reaction to obtain the epoxy curing agent. The epoxy curing agent has the advantages that the epoxy curing agent can be mixed with epoxy resin to prepare an epoxy resin composition for the concrete refinishing paint; sulfydryl, tertiary amine and phenolic hydroxyl in the molecular structure of the curing agent have synergistic promotion effect, and accordingly, the epoxy curing agent can cure the epoxy resin below minus 25 DEG C and has high adhesion to concrete materials.