The present invention relates to a slump-retaining polycarboxylate superplasticizer with weight-average molecular weight of 20,000 to 80,000, which is obtained through polymerization reaction of monomer A, monomer B, monomer C and monomer D in aqueous solution with the existence of redox initiator, the molar ratio of (monomer A + monomer B) : monomer C : monomer D is 1 : 3-8 : 4-12, wherein the molar ratio of monomer A and monomer B is 1 : 1-4. The superplasticizer of the present invention has excellent slump retention capacity with low dosage, which can both meet the need for quick compensation of high performance concrete at an early age, and also can meet the need of long-term slump retention, effectively improving the effect and adaptability of a slump-retaining polycarboxylate superplasticizer.
