Study on the activity of flame retardant, halogen flame retardant decabromodiphenyl oxide (DBDPO) and the two synergistic effects on flame retardant properties and mechanical properties of glass fiber / epoxy resin composite material.The results show that the amount of the active flame retardant of the composite material is obviously lower than that of halogen flame retardant.When the ratio is 1∶1, can play a very good synergistic effect, the oxygen index of the composite can reach 28, compared to only add halogen flame retardants reach same flame-retardant properties of composite its mechanical properties are improved significantly.