The effects of SiC particle size, volume fraction and tensile strain on the deformation behaviors of SiC particle reinforced Al matrix composites were studied by finite element method using microstructure based model. The results showed that the addition of reinforcements will result in no-uniform stress distribution in matrix. The maximum stress in the particles increases, and the minimum stress in the matrix decreases when the SiC particle volume fraction increases, indicating more load being transferred from matrix to particles with increasing the SiC particle volume fraction. It also showed that as the tensile strain and SiC particle size increase, the maximum stress in the particles increases. It can thus be concluded that small-sized SiC particles can endure more loads and improve the mechanical properties of the composites.