The architecture of microstructure. i.e., volume fraction, size, shape, orientation and arrangement geometries of constituents, affect the stress and strain partitioning of the constituents. A numerical method was presented in this paper for calculation of stiffness tensor of particulate reinforced composites having continuous matrix including spherical particulate. The arrangement effects of spherical particulate on the stiffness tensor of particulate composites were estimated. The estimation of numerical calculations were very good agreement with results of finite element method (FEM) and Mori Tanaka Method (MTM). Numerical method presented can consider arrangement effects of reinforcement particulate via a simple parameter named as geometrical factor (Gf). The important advantage of numerical method proposed in this work is to allow the systematic and parametric investigation of the effects of microstructural geometry on the elastic behavior of particulate composites.