The mechanical properties of the extruded profiles depend on the final microstructure distribution in the extrusion process. To investigate the effect of the stain-rate and temperature on the microstructure distribution of the aluminum profiles, the aluminum profile with different wall thickness was studied by metallographic experiment and numerical simulation. The result showed that the distribution of fine equiaxed grain developed by the complete process of primary recrystallization and coarse grain developed by secondary recrystallization was consist with the distribution of temperature and strain-rate. The variation gradient of the strain-rate was the key factor which determines the distribution of microstructure in thick wall section. Compared with thick section, the higher strain-rate is the key factor that leads to secondary recrystallization, but lower temperature prevents complete process of recrystallization. in thin wall section.