The invention discloses a concrete curing agent, which comprises the following components in parts by mass: 20-25 parts of styrene-acrylic emulsion, 7-10 parts of acrylamide solution, 7-9 parts of sodium silicate solution, 6-9 parts of organic silicon solution 8 parts, 1-3 parts of methyl methacrylate, 1-3 parts of polyethylene glycol monomethyl ether acrylate, 3-5 parts of polyethylene glycol, 1-3 parts of polyvinyl alcohol, 4-6 parts of styrene , 6-8 parts of methyl acrylate, 5-7 parts of butyl methacrylate, 3-5 parts of butyl acrylate, 4-6 parts of ethyl methacrylate, 1-3 parts of ammonium thiosulfate, EPDM 1-3 parts of rubber, 0.7 parts of butyl citrate, 1 part of soda ash, 0.5 parts of gypsum powder, 0.1 part of periodate lignin, 0.1 part of surfactant, 0.2 part of defoamer, 0.3 part of leveling agent and benzene 1 part methanol. The curing agent disclosed by the invention can effectively prevent water loss inside the concrete, and is environmentally friendly and pollution-free.