Abstract: In this paper, a masterbatch was prepared by introducing phenyl silicone oil and titanium dioxide into a blend of polypropylene and an intumescent flame-retardant SR-50A (PP/IFR) through extrusion. When the content of masterbatch in polypropylene was 20 wt%, the limited oxygen index value of the system reached 35.6 %, and all the samples reached UL 94 V-0 grade. Thermal gravimetric analysis showed that the addition of phenyl silicone oil promoted the decomposition of flame retardant in the initial stage and reduced the thermal decomposition rate of PP. Titanium dioxide promoted the char formation. The addition of phenyl silicone and titanium dioxide had little influence on the mechanical properties of the composites.