RC-90 calcined kaolin is surface treated provides ultra-fine particle size, good dispersion stability, small screen residue, good reinforcing performance, high specific surface area and the unique structure of the microporous sheet. It is widely used in rubber as the partial substitution of carbon black having a good reinforcement and abrasion resistance, improved thermal stability, acid- alkaline resistance, and mechanical properties. Meanwhile, it is very cheap, using as filler can reduce production cost significantly.