The invention discloses a super controlled release type polycarboxylate slump retention agent and a preparation method thereof. The preparation method of the polycarboxylate slump retention agent comprises the following steps: carrying out free radical polymerization on a monomer A, namely polyoxyethylene ether (TPEG), a monomer B, namely maleic anhydride or polyethylene glycol maleic acid esters, a monomer C, namely acrylic acid, a monomer D, namely hydroxyalkyl acrylate or vinyl acetate, an initiator, a chain transfer agent and water, adding an alkaline liquor to neutralize the mixture, wherein a molar ratio of the monomer A to the monomer B to the monomer C to the monomer D is 1 to (1.0-2.5) to (1.0-2.5) to (2.0-4); the dosage of the initiator accounts for 1%-8% of the total mole number of the monomer A, the monomer B, the monomer C and the monomer D; the dosage of the chain transfer agent is 1%-3% of the total mole number of the monomer A, the monomer B, the monomer C and the monomer D. The super controlled release type polycarboxylate slump retention agent disclosed by the invention is in a liquid state, has solid content of 50%, and has performances of low alkaline content, a low water-reducing rate and excellent slump retention performance. Besides, the production process is simple, the reaction conditions are easy to control, and the environmental pollution is avoided.