Styrene-butadiene rubber (SBR) vulcanizates with graded network chain densities were prepared by a conventional method of rubber science and technology. The characteristics of the gradient and gradient direction of the network chain density were examined from the perspective of the mechanical properties of the graded SBR vulcanizates. In the matrix of the graded SBR vulcanizates, silica particles were generated in situ, and the tensile properties were investigated.