The HKUST-1@APP was prepared by loading HKUST-1〔Cu3(BTC)2, BTC means trimesic acid〕on the surface of ammonium polyphosphate (APP) via solvothermal method. The flame-retardant composites (HKUST-1@APP/EP) were prepared by mixing different amounts of HKUST-1@APP with epoxy resin (EP). The flame retardant and mechanical properties of EP composites were investigated by horizontal and vertical combustion tester,, oxygen index tester, electronic tensile machine, et al. The results showed that while adding 5% of HKUST-1@APP, the limiting oxygen index of EAC-5 was 27.5%, and the vertical combustion test (UL-94) passed the V-1 level. The AD/AG(the peak area ratio of D and G peaks formed by the vibration of carbon atoms in amorphous carbon and SP2 hybrid carbon atoms in graphite carbon in Raman spectrum)of the residual char was reduced to 0.043 compared to 0.3161 of EA-5 which was added 5% APP. It indicated that HKUST-1@APP could improve the char layer produced during combustion and make the char layer more continuous and graphitized.