Composite is a mixture of two or more different materials which differ in composition and intrinsic properties that make a good bond with each other And create the properties that each of the constituent materials cannot produce those properties a lonely. In this research, Aluminum matrix composite was produced by addition of gel produced by the BS290 polymer silicon. The parameter studied in this research is the type of additive reinforcement to the aluminum melt and investigation this effect on the mechanical and structural properties of the aluminum matrix. At the first, the sol-gel method of the BS 290 polymer was used to create the reinforcing phase. By using the sol-gel method, SiOC (Silicone oxy Carbide) nanoparticles with an average length and width of 87 and 68 nm was synthesized. Powder metallurgy was used to determine the effect of synthesized particles on aluminum matrix. The synthesized nanoparticles were added to the pure aluminum powder by 1 and 2 wt.%, and after composite manufacturing process and hot extruding, the mechanical properties were studied. After investigating the effect of the SiOC reinforcing phase on the Aluminum matrix, the type of additive reinforcement to the Aluminum melt and final properties such as mechanical and structural of composite was investigated. In order to characterize the composite, hardness, compression, tensile, X-ray diffraction and DTA thermal analysis were used, and for microscopic examination, optical and electron microscopy were used. Finally, it was found that the microhardness, yield strength and compressive strength properties were 47, 52, and 18% increase, which determined the successful incorporation of particles from the pyrolysis of the polymer into the melt and that these particles play reinforcement and nucleation site in Aluminum matrix. Keywords: Composite, in-situ, Aluminum, powder metallurgy, polymer, sol-gel, BS-290