Urea　formaldehyde/epoxy　resin　microcapsules　were　prepared　by　an　in　situ　polymerization　method　and　the　effect　of　emulsifier　on　the　syntheses　process　of　the　microcapsules　was　discussed.　The　surface　morphology　of　the　microcapsules　was　observed　by　optical　microscopy　and　scanning　electron　microscopy　(SEM).　Chemical　structure　was　characterized　by　Fourier　transform　infrared　spectroscopy　(FTIR).　Thermal　stability　was　obtained　using　simultaneous　thermal　analysis　(STA).　The　microcapsules　were　composed　of　urea-formaldehyde　resin　shell　and　epoxy　resin　core.　Emulsifier　played　an　important　role　in　the　polymerization　process　when　the　core　material　was　packed　by　pre-polymer,　so　the　effects　of　different　emulsifiers　(OP-10,　SDS　and　SDBS)　were　discussed　respectively.　Results　showed　that　the　particle　size　of　the　microcapsules　was　uniform　when　SDBS　as　an　emulsifier.　Microcapsules　showed　good　thermal　stability　below　240　degrees　C　and　the　initial　decomposition　temperature　of　the　microcapsules　was　265　degrees　C.　The　core　materials　released　after　microcapsules　rupturing,　which　could　be　proven　by　the　images　of　SEM.　When　implanted　in　cementitious　composites,　complete　shape　of　microcapsules　and　good　interface　between　microcapsules　and　cement　specimen　substrate　could　also　be　observed.