Abstract: Based on molecular structure design theory, a polycarboxylic acid superplasticizer with high slump retaining performance was prepared by free radical polymerization with acrylic acid and acrylamide in the Redox system of sodium erythorbate/Na₂SO₃ and Fe²⁺, using ethenyloxy polyoxyethylene ether with double bond directly connected with oxygen atom as polymeric monomer. The results showed that the ethenyloxy-polyoxyethylene ether has higher polymerization activity than conventional polyether monomer due to its C＝C double bond directly connected with oxygen atom, and the time of induction period can be shortened by nearly 1/2. The initial and 1 h slump of the prepared concrete can be increased by 16% and 64%, respectively, compared with conventional water reducing agents. However, the initial and 1 h slump expansion were 7% and 22% higher. The FT-IR spectra showed that the amide group and carboxyl group of the functional monomers were successfully grafted on the main chain of polycarboxylic acid superplasticizer.