Polypropylene (PP) composite which was filled with kaolin (KL) or magnesium hydroxide or ammonium polyphosphate (APP) was prepared.The best binary composite which was mixed with a certain amount of PP-g-MAH was also investigated.Every composite' s mechanical properties and oxygen index(OI) were determined.Finally,the optimal formula was confirmed.It showed that the OI properties was improved with the increase of flame retardant agents.The effect of flame retardant with different inorganic flame retardants was better than alone,and the mechanical properties would not drop a lot.After adding PP-g-MAH,the impact strength was increased significantly,and the oxygen index was little changed.The optimal formula was PP/Mg(OH) 2/KL/PP-g-MAH (100/40/10/5).