Polymaleic　acid　was　synthesized　in　water　phase　by　adopting　maleic　acid　as　raw　material　and　H2O2　as　initiator.　Then　a　novel　polycarboxylate　superplasticizer　of　PMA-AA-AMPS　was　synthesized　by　using　polymaleic　acid　(PMA),　acrylic　acid　(AA)　and　2-acrylamido-2　methyl-propane　sulfonic　acid　as　raw　materials,　ammonium　persulfate　as　initiator　in　aqueous　media.　Additionally,　the　polymerization　conditions　were　optimized.　The　results　indicate　that　the　copolymer　can　be　prepared　under　such　optimum　conditions,　i.e.,　6:3:1.2　molar　ratio　of　MA,　AA　and　AMPS,　8%　of　the　mass　fraction　of　ammonium　persulfate,　6%　of　the　mass　fraction　of　formate　sodium,　85°C　of　the　polymerization　temperature　and　3　h　of　the　reaction　time.　The　characterization　results　of　FTIR　indicate　that　the　prepared　terpolymer　contains　functional　anionic　groups　such　as　carboxyl,　hydroxyl,　sulphonate　and　amido　groups.　The　number　average　molecular　weight　of　the　PMAAA　from　GPC　is　5743　g/mol　occupying　81.36%　of　the　whole　mass　fraction.