A new phosphorus intumescent flame retardant 6-amino-1,3,5-triazine-2,4 -diaminium 2,3,4,5,6-pentahydroxyhexanoate dihydrogenphosphate(ATDPDP) was synthesized using sodium gluconate, phosphoric acid and melamine as raw materials. The structure was characterized by FTIR and MS. The effects of ATDPDP and APP on flame retardancy, thermal behavior and mechanical properties of epoxy resin (EP) were investigated by limiting oxygen index (LOI) test, UL-94 vertical test, TG and mechanical property test, respectively. The observed data showed an effective flame retardancy with a LOI value of 29.6% and UL-94 V-0 rating when the weight ratio of ATDPDP/APP（1∶1）is only 10% in epoxy resin systems. The morphology of residue after LOI test was investigated by scanning electronic microscopy (SEM), which displayed a well compact swell char layer. The combination system of ATDPDP/APP displayed obviously better ability of char formation and better mechanical properties than acting independently.
