A phosphorus-nitrogen flame retardant curing agent phenyl phosphonic m-Xylylene diamine diamide(PPMXD) was synthesized by phenylphosphonic dichloride(PPDC) and m-Xylylenediamine (MXDA), The chemical structure of the obtained compound was identified by FT-IR、1HNMR、ESI-MS. The thermal stability of PPMXD was tested by DSC and TG. The effects of mole ratio of reactants, reaction temperature and time, the solvent dosage and the type of solvent were investigated． The experimental results demonstrated that the yield of PPMXD was maximum when the reaction temperature was 20℃, the reaction time was 7h, n(PPDC):n(MXDA)=1:3.5, methylene chloride and N,N dimethylformamide was used to be mixed solvent which quantity ratio of methylene chloride to N,N dimethylformamide was 2.3:1, m(solvent)：m(PPDC)=12：1. The PPMXD was used in epoxy, TGA and SEM would study the thermal properties and the epoxy resin carbon residue morphology. The flame retardant properties of epoxy resin were tested by limiting oxygen index (LOI) and vertical experimental characterization of the combustion. When the addition of PPMXD was 28.5%, it could through the UL-94 V-0 test, the oxygen index could reach 29%, the tensile strength and impact strength could reach 42.89MPa and 6.45KJ/m2, respectively. The results of TGA showed that compare with EP, the addition of PPMXD could make the largest thermal decomposition rate of EP2 decrease from 18.93%/min to 13.28%/min, at the same time, the amount of residual carbon at 800℃ also increased from 16.12% to 18.86%. The SEM results show that the surface of the epoxy resin after buring was rough and foamed obvious, which performed good flame retardancy.