A series of styrene butadiene rubber (SBR) composites based on modified kaolin were prepared by melt blending method. Vulcanization properties, mechanical properties and microstructure of the kaolin/SBR composites were characterized and analyzed. The results show that the modified kaolin greatly advances vulcanization properties of SBR composites, and the M-6 modifier has the best modified performance. The scorch time (t₁₀) and vulcanizing time (t₉₀) of SBR composites are shortened with reduction of kaolin particle size, meanwhile, the tensile strength and stretching stress of 300% are improved. With increase of the kaolin content, t₁₀ and t₉₀ of SBR composites gradually reduce, and mechanical properties of SBR composites improve. With the kaolin content of 80 phr, the tensile strength, tear strength and stretching stress of 300% reach 19.62 MPa, 40.63 kN/m, 6.73 MPa respectively, which increase 11.70 times, 3.79 times and 6.73 times respectively compared with pure SBR. The kaolin with lamellar structure is finely and disorderly dispersed in the SBR composite matrix by analyzing the microstructure of SBR composites, based on this, the reinforcing mechanism of modified kaolin was preliminary explained.