With the combination of high energy ball milling method and semi-solid extrusion method, in this paper the technique of preparing sub-micron particle strengthening aluminum matrix composite was developed firstly. Through the semi-solid instrument devised by ourselves, sub-micron SiCp/2014Al and SiCp/6066Al composites were prepared by the utilization of high energy ball milling- semi-solid extrusion method. Optical microscopy, scanning electron microscopy, universal material testing machine, thermal analyzer and Vickers hardness tester were used to study the microstructure, mechanical and thermal physical properties of sub-micron SiCp/Al composites. Through the analysis of microstructure and properties of materials, the influence of different solvents on dispersion effects of sub-micron particles in matrix, the influence of semi-solid extrusion parameters on microstructure and properties of materials, strengthening mechanism , fracture mechanism , aging hardening behavior of sub-micron particles strengthening aluminum matrix composites were studied in this paper. The main conclusions were as follows:1. Sub-micron ceramic particles owned the excellent strengthening effect. In a certain range of strengthening particles volume fraction, mechanical properties of sub-micron particle strengthening aluminum matrix composites increased with the increasing of the volume fraction of strengthening particles, however, when the volume fraction of strengthening particles was excessive, gathering area of strengthening particles and interface between strengthening particles in composites would worsen the mechanical properties of materials.2. With the increasing of volume fraction of sub-micron strengthening particles, the main microscopic fracture mechanism of composites changed as the following sequence: "fracture of matrix → fracture of interface between strengthening particles and matrix → fracture between strengthening particles".3. The optimal semi-solid extrusion temperature was the temperature of matrix when volume fraction of liquid phase reached 40% inAbstractcomposites; Increasing of extrusion ratio was beneficial to the improvement of mechanical properties of composites.4. For three organic solvents of acetone nor-butanol and ethanol, acetone owned the best dispersion effect on 0.1 3 [am SiC particles during the process of blending. Taking acetone as the blending medium the composites had the optimal properties.5. Dispersed sub-micron particles didn"t influence the aging kinetics of matrix alloy, the peak aging time of composites was the same with that of matrix alloy. While the volume fraction of particles was excessive, large size particle aggregates played a role that micron strengthening particles accelerated the aging precipitation in matrix alloy.6. Sub-micron SiCp/Al composites prepared by high energy ball milling and semi-solid extrusion techniques owned excellent particle dispersion ability, and the materials owned excellent mechanical and thermal physical properties.