The　study　of　polymerization　in　methyl　methacrylate　(MMA)/acrylic　acid　(AA)　oil-in-water　microemulsions　stabilized　by　sodium　dodecyl　sulfate　and　OP　emulsifier　was　carried　out　by　using　dilatometry　with　potassium　permanganate　as　initiator.　The　influence　of　initiator　type,　reaction　temperature,　the　concentration　of　initiator　or　monomer　and　the　mass　ratio　of　AA　to　MMA　on　the　monomer　conversion　and　the　rate　of　polymerization　was　investigated.　The　results　showed　that　the　monomer　conversion　and　the　rate　of　polymerization　using　potassium　permanganate　as　initiator　was　similar　to　that　using　potassium　persulphate　but　much　higher　than　that　using　2.2′-azobisisobutyronitrile.　Keeping　the　constant　composition　of　microemulsion,　the　rate　of　polymerization　and　final　conversion　increased　first　and　then　dropped　with　increasing　temperature,　and　the　total　apparent　active　energy　was　-82.7　kJ/mol　above　35°C.　The　rate　of　polymerization　and　final　conversion　increased　and　reached　maximum　with　increasing　the　concentration　of　potassium　permanganate.　And　peak　polymerization　rate　and　maximal　final　conversion　appeared　with　increasing　the　concentration　of　monomer　or　the　ratio　of　AA　to　MMA.　In　addition,　the　period　of　constant　rate　during　polymerization　was　observed　at　appropriate　conditions.