Abstract: A novel triazine-based charring agent (CA-ODA) with alternative triazine ring and benzene ring as main chain was prepared from cyanuric chloride and 4, 4 ’- diaminodiphenyl ether, and then mixed with ammonium polyphosphate (APP) to act as the flame retardancy of polypropylene (PP). The effects of different mass ratio of APP/CA-ODA system on the thermal stability and flame retardancy of PP were studied by thermogravimetric analysis and cone calorimeter. The results indicated that CA-ODA has good thermal stability and excellent charring performance, alternative triazine ring and benzene ring could accelerate the charring performance of PP, so the APP/CA-ODA system improved the flame retardancy of PP effectively. When the total content of APP/CA-ODA was 25%, and the mass ratio of APP to CA-ODA was 2:1, the peak of heat release rate of PP was reduced from 1046 kW?m-2 to 334 kW?m-2, and the char residue could reach to 41.5 %.