The microcapsules containing triphenyl phosphate (TPP) flame retardant have been prepared by using the epoxy resin (Novolac Type) with good physical properties and network structure. The reactants including TPP, epoxy resin and mixed surfactants were emulsified to oil in water (O/W) by the phase inversion technology and then conducted on the crosslinking of epoxy resin by In-situ polymerization. The capsule size and size distribution of TPP microcapsules was controlled by mixed surfactant ratio. The thermal property of TPP capsules were measured by the TGA. The morphology and capsule size were also investigated by the SEM respectively. TPP capsules with 1:1 of mixed surfactant (F127:SDBS) ratio were more spherical and uniform than it with others. The TPP capsule size was 12 ~ 17 μm and TGA results shows that TPP capsule efficiency was about 73%.