Abstract: Melamine phosphate hybrid (CNMP) was synthesized by liquid phase reaction using melamine, phosphoric acid and graphitic carbon nitride (g-C3N4) as raw materials, and then a solid phase thermal condensation reaction was conducted for CNMP to obtain final product, melamine polyphosphate hybrid (CNMPP). The structure and thermal properties of the final product were characterized. The flame retardant polyamide 6 (FRPA6) was prepared by using CNMPP, and its flame retardant performance of FRPA6 was evaluated by vertical burning test, limiting oxygen index (LOI) test and glow-wire test. The results indicated that CNMPP achieved a better thermal stability than melamine polyphosphate (MPP). CNMPP obtained an increase in initial decomposition temperature at a weight loss of 5 wt% by 8.5 ℃, and its char yield was also improved from 34.1 wt% to 60.2 wt% at 650 ℃. The hybridization of MPP with g-C3N4 further improved the flame retardant performance of polyamide 6. With the addition of 30 wt% CNMP with a low hybridization level, the resulting FRPA6 achieved shorter self-extinguishing time than that with MPP. The FRPA6 also achieved a UL 94 V-0 classification rating, and its LOI value was improved from 24.2 vol% to 29.5 vol%. Moreover, the glow-wire ignition temperature of FRPA6 increased as well. However, the flame retardant performance of FRPA6 became deteriorated when the CNMPP with a high hybridization level was incorporated.