Abstract: In order to improve the density and mechanical property of 6061 aluminum alloy prepared by powder metallurgy, hot extrusion process was applied to the 6061 alloy in sintered state. The effect of hot extrusion on microstructure and tensile strength of 6061 aluminum alloy was researched. The results show that the microstructure of the aluminum alloy in sintered state was equiaxed grain distributed uniformly. After hot extrusion, the grains were distributed like bandings and grain size decreased. The relative density of the aluminum alloy in sintered state was 96.67% and relative density of the aluminum alloy after hot extrusion increased to 98.14%. The tensile strength increased from 112 MPa to 248 MPa after hot extrusion. The fracture type of the aluminum alloy in sintered state was ductile fracture and fracture type of the aluminum alloy in hot-extruded state was mixed mode of ductile fracture and intergranular fracture.