The invention discloses an efficient slump retaining agent, which is prepared from the following components in parts by weight: 250-600 parts of a monomer A, 11-40 parts of a monomer B, 20-60 parts ofa monomer C, 5-15 parts of a monomer D, 1-20 parts of an initiator, 0.8-10 parts of a composite molecular weight regulator, 0.5-4 parts of vitamin C sodium and 300-700 parts of water, wherein the monomer A is any one or a mixture of more of isopentenyl polyethylene glycol ether, hydroxybutyl vinyl polyethylene glycol ether and ethoxy vinyl polyethylene glycol ether, the monomer B is any one or amixture of two of acrylic acid, fumaric acid, itaconic acid and maleic anhydride, the monomer C is any one or a mixture of more of hydroxyethyl acrylate, hydroxypropyl acrylate, methacryloyloxy phosphate and hydroxyethyl methacrylate, the monomer D is diacrylamide dimethyl propanesulfonic acid or acrylamide, and the composite molecular weight regulator is mercaptoethanol. The components are subjected to a stirring reaction to obtain the product. The efficient slump retaining agent provided by the invention is good in slump retaining performance, small in performance fluctuation and excellent in adaptability, and can effectively meet the slump retaining requirements of concrete in various regions.