Abstract:: The 6063Al-xAl2O3 (X= 0,2,4,6) composite was prepared by the method of near liquid line casting using CuO-Al as the reaction system to form Al2O3 particles in the in-situ reaction of 6063 aluminum alloy. The influence mechanism of the shape, size, quantity, distribution and interface characteristics of in-situ reaction particle Al2O3 and in-situ crystallization particle Mg2Si of 6063 aluminum alloy on the microstructure and wear resistance of the alloy was studied. The results show that near spherical θ-Al2O3 particles with sub-micron size are formed in the in-situ reaction of 6063 aluminum alloy. The (311) crystal plane has a coherent interface with the (111) crystal plane of 6063 aluminum alloy matrix. The size of Mg2Si in 6063 aluminum alloy is about 100nm, which is banded, and its (02-2) crystal faces with Al matrix (111) belong to coherent interface. With the increase of the content of Al2O3 particles, the grain morphology of 6063 Al matrix composites changes from rose-like to equiaxed grain gradually, and the grain size decreases gradually. When the mass fraction of Al2O3 is 6%, the microstructure of the composite is composed of equiaxed grains and fine columnar grains. When the load is 50N, the wear of 6063 aluminum alloy is 6.72mg, and the wear of 6063-6Al2O3 composite is 1.63mg, which is 75.7% lower than that of 6063 aluminum alloy. The in-situ particles (Al2O3+Mg2Si) form a coherent interface with the aluminum matrix. There is no pollution between the interfaces and the interface bonding strength is high. In the wear process, it is not easy to fall off from the matrix and bear most of the load in the wear process. The synergistic effect of in-situ formation of high hardness Al2O3 particles and in-situ crystalline particles Mg2Si can improve the wear resistance of composites. When the applied load is 40N, the wear mechanism of the composites changes from adhesion wear to abrasive wear with the increase of the mass fraction of reinforcement phase. The wear mechanism of 6063 aluminum alloy is mainly serious adhesion wear. The wear mechanism of 6063-2Al2O3 composites is mainly adhesive wear, and the wear of 6063-4Al2O3 and 6063-6Al2O3 composites is mainly abrasive wear.