Polycarboxylate　ether　(PCE)　based　superplasticizer　was　synthesized　in　aqueous　solutions　containing　methyl　allyl　polyethylene　glycol　(MAPEG)　as　macromonomer　and　acrylic　acid　(AA),　ammonium　persulfate　(APS)　as　initiator.　The　conversion　rate　of　macromonomer　at　different　time　was　determinted　by　measurement　of　the　concentration　variation　in　the　MAPEG-AA　copolymerization　system　by　means　of　Gel　Permeation　Chromatography　(GPC)　and　High　Performance　Liquid　Chromatography　(HPLC),　and　the　effect　of　reaction　conditions　on　the　polymerization　rate　was　explored　and　discussed.　The　results　showed　that　the　polymerization　rate　was　increased　with　the　augment　of　feeding　amount　of　monomer　AA　(reactant),　APS　(initiator),　and　the　reaction　temperature,　but　was　decreased　with　augment　of　feeding　amount　of　MAPEG.　The　kinetics　equation　of　polymerization　reaction　was　established　as　RP　=　K[AA]0.15[MAPEG]-0.65[APS]0.76　for　the　MAPEG-AA　copolymerization　system　using　APS　as　the　initiator.　The　reaction　activation　energy　(Ea)　of　polymerization　was　calculated　under　this　condition.　©　American　Concrete　Institute.　All　rights　reserved.