Recently, a large number of metal matrix composites have been developed for high-performance applications. The first requirement for superior performance of a composite material is the homogeneous distribution of the reinforcing phase. In particulate-reinforced composites, any agglomeration of reinforcement particles deteriorates the mechanical properties of composite. Stir casting route has been used to achieve homogeneity of particle distribution throughout the matrix. In present study, ZrSiO₄ and TiB₂ particles were incorporated in A356.1 alloy. The size of ZrSiO₄ and TiB₂ particles was 1μm. Reinforcement particles were added to melted aluminum at different temperatures above pure aluminum melting point (750, 850, 950°C). The volume fraction of reinforcement particles was 5%. After addition of reinforcement, stirring was continued for 12min for better distribution and better solidification conditions. The microstructure and mechanical behavior of prepared composites were studied. Scanning electron microscopy and X-ray diffraction were used to investigate dispersion of reinforcement particles in aluminum matrix and chemical composition of composites. Hardness and tensile tests were carried out to test mechanical properties. The results of these experiments show that the mechanical properties and microstructure of composites were changed by increasing temperature; also the best condition of ZrSiO₄ case was 750°C but 850°C for TiB₂.