Abstract: Taking isoamyl alcohol polyoxyethylene ether（TPEG）,maleic anhydride and sodium methylacrylsulfonate as main monomers,potassium persulfate as free radical initiator,water as solvent,synthesized a new polycarboxylate series disperant of the coal water slurry with a free radical polymerization.The radical polymerization reaction would be influenced by many factors.Analyse these factors by orthogonal design.The optimum conditions of synthetized dispersant is that,the ratio of isoamyl enol ethoxylates and maleic anhydride is 1.0 ∶2.4,the dosage of SMAN is 0.32,the potassium persufate content of initiator is 4 percent,the reaction time is 40 minutes,the reaction temperature is 80 ℃.Under the best reaction condition,the coal water slurry has lower viscosity and better stability.