Abstract: The encapsulated mica with zinc stannate(ZS/Mica) was prepared by a coprecipitation method, and then the resultant ZS/Mica was modified by KH550/paraffin wax and KH550/sebacic acid to form two types of mica-based flame retardants(P-ZS/Mica and S-ZS/Mica). X-ray powder diffraction, scanning electronic microscopy and electron energy spectroscopy were conducted to confirm the successful encapsulation of zinc stannate on the surface of mica particles. Such mica-based flame retardants were used to replace Sb2O3 in bromide-antimony flame-retardant polypropylene(PP) system. The results indicated that flame retardancy of the flame-retardant PP maintained unchanged but its thermal stability increased when half amount of Sb2O3 was substituted by P-ZS/Mica. However, the elongation at break, impact strength and flexural strength of the flame-retardant PP increased by 55 %, 32 % and 30 %, respectively. Moreover, the flame-retardant PP also showed a little change in peak value of heat release rate but gained a significant reduction in the amount of released smoke.