In this paper, using maleic anhydride (MA), allyl polyethylene glycol (AP), methyl allyl sulfonate (SM) as monomer and ammonia persulfate (KPA) as initiator, a polyether high-performance water-reducing agent for polyglycolic acid (PR) on good compatibility in sulphoaluminate cement (SAC) was synthesized by solution polymerization and orthogonal design. And the effects of various factors (reaction time, branched length and density of PR etc.) on the performance of PR were also studied. Results show that the optimum formula was as follows: the polymerization degree of AP was 56, the mass molar ratio of three monomers was n (MA): n (AP): n (SM) = 3:2:1, the amount of AP accounted for 9% of the total molar content of monomer, the reaction temperature was 65 °C, and the reaction time was 5 h.