The invention provides an anticorrosive agent for concrete. The anticorrosive agent is a mixture of powder selected from the group consisting of fly ash, blast-furnace water-quenched slag powder, silica fume, light-burnt metakaolin powder, phosphorus slag powder, alum slag powder, natural zeolite powder and the like and a barium compound selected from the group consisting of barium chloride, barium nitrate, barium acetate, barium hydroxide, barium sulfide and the like. The anticorrosive agent for concrete provided by the invention enables Ca(OH)2 by-produced in hydration of cement to bond with SiO2 included in cement so as to produce secondary hydrated calcium silicate, so the strength and impermeability of concrete are improved; barium ions doped into concrete reacts with SO4<2-> from the outside in time to produce inertial and stable secondary barite, so deionization of SO4<2-> is realized and corrosivity of SO4<2-> is eradicated; the secondary barite forms a stable mineral inorganic protection film on the surface layer of concrete, so further invasion of external harmful ions is prevented, the strength, impermeability and corrosion resistance of concrete are further improved, the service life of concrete is substantially prolonged, and economic benefits are increased.