Through orthogonal experiment design, the flame retardant effects of the following elements on flame retardant paper were discussed including the compound flame retardants’ type, mass concentration and pH value, reaction temperature, reaction time and mass concentration of LDHs. The research results showed that under the condition of the mass concentration of melamine(MA) being 10 g/L, pH value 7.0, reaction temperature 50 ℃, reaction time 15 min, and the mass concentration of LDHs 30 g/L, the oxygen index (LOI) of flame retardant paper was 31%. The flame retardant effect has been increased by 72% as compared with the blank sample base paper with LOI of 18%.