Abstract: PA6 was flame-retarded with melamine polyphosphate (MPP) and melamine octomolybdate (MOM). The limiting oxygen index, UL 94V flame retardancy and thermal stability of the flame-retarded PA6 were measured. Fourier transform IR and SEM techniques were used to analyze the pyrolysis residue and cone calorimeter was applied to determine a number of combustion parameters closely related to fire safety, including the peak heat release rate, average heat release rate, total heat rate, effective combustion heat and mass loss rate, specific extinction area etc., all of them are decreased clearly besides the specific extinction area. In addition, the elemental composition of the pyrolysis residue on the PA6 surface and the corresponding XPS data were obtained using XPS technique. Experimental results have shown that the limiting oxygen index and UL 94V flame retardancy of PA6 flame-retarded with 27%(mass fraction) of MPP-MOM reach 35.3% and V-0 grade, respectively. Simultaneously, it has also been shown that the synergistic flame retardancy of MOM to MPP is very good.