Abstract: The synthesis process with low-energy consumption is an important developing direction for green synthesis of the water reducing agent. Developing a high slump retaining type of polycarboxylate superplasticizer has an important practical significance in solving the problems of the slump loss control in the modern concrete construction. A compound redox system was used to synthesize the high slump retaining type of polycarboxylate superplasticizer with one step method at 20 ℃, by using the isopentenol polyoxyethylene ether, butyl acrylate, hydroxyethyl acrylate and acrylic acid as a comonomer. The effects of the butyl acrylate, hydroxyethyl acrylate, chain transfer agent, reducdant and oxidant on the dispersing ability and slump retaining ability of the superplasticizer were studied by a single factor and orthogonal tests. The optimum synthetic process parameters are as follows: the equimolar substitution amount of acrylic acid replaced by the butyl acrylate and hydroxyethyl acrylate is 30%, the usage of the chain transfer agent, reductant and oxidant is 0.25%, 0.22%, 0.33% respectively (with the mass ratio of the isopentenol polyoxyethylene ether), and the reaction time is 4 hours. Compared with foreign similar products, the test results show that the developed superplasticizer has a small slump retention ability and lower dosage sensitivity, which is especially suitable for the low-slump concrete needing high slump retaining ability.