In-situ nanoparticles reinforced Al matrix composites had low density，high modulus and high strength，making them one of the key materials for achieving lightweight equipment structure.The amount of plastic deformation during processing is an important factor determinging the microstructure and properties of aluminum matrix composites. Scanning electron microscopy and backscattered electron diffraction techniques were used to analyze the particle distribution and three-dimensional grain structure in composites， as well as the evolution law with extrusion deformation.The room temperature tensile performance and fatigue resistance of composite materials under different organizational structures were discussed. The results show that TiB2/7050Al composite have high elastic modulus （78-84 GPa）， high plastic yield （6588 MPa ·%）， and high fatigue limit （289 MPa）， and will have broad application prospects in aerospace and other fields.