A novel halogen-free fame-retardant system,which is consist of the synthesized intumescent flame retardant(M-IFR)and coating red phosphorus(RP),was used for the flame retardation of ABS.The flame retardancy of the resulting flame retardant system was investigated by LOI,UL94 and Cone Calorimeter,respectively.The results show that when a mass ratio of M-IFR to RP is 8:5 and their total loading is 26wt%,the flame-retardant ABS system has very good flame retardancy:LOI 24.5 % and UL-94 V-0 rating.Based upon the cone calorimeter test,it can be found that the flame-retardant ABS system has much lower PHRR,THR and AMLR and longer tign,than neat ABS.Therefore,the novel halogen-free fame-retardant system is a very promising system for the flame retardation of ABS.