The invention relates to a method for preparing a delayed coagulation type super plasticizer through atom transfer radical polymerization. The method comprises the steps of with a delayed coagulationtype monomer and a carboxylic acid small monomer as main reaction raw materials, sequentially carrying out atom transfer radical polymerization (ATRP), alcoholysis and copolymerization so as to prepare the delayed coagulation type super plasticizer, namely that carrying out atom transfer radical polymerization (ATRP) on the delayed coagulation type monomer as a reactant under the system formed byan unsaturated initiator, transition metal halide and a ligand so as to obtain an unsaturated macromonomer, carrying out alcoholysis so as to obtain a delayed coagulation type macromonomer, and copolymerizing with the carboxylic acid small monomer, so as to obtain the delayed coagulation type super plasticizer. According to the method, a functional side chain consisting of delayed coagulation typestructural monomers is innovatively designed and synthesized by virtue of a controllable polymerization technical measure, a traditional polymer side chain structure is replaced, the super plasticizer presents excellent capacities of dispersing element purified slurry, and the coagulation time of the element purified slurry can be remarkably delayed, so that the later-period strength of concreteis improved, and multiple effects of high water reduction, slump resistance and delayed coagulation are achieved.