The evolution of microstructure in Al-Mn alloy with a low ratio of Fe/Si produced by twin-roll casting (TRC) during various homogenization treatments has been investigated. The grain structure near the surface transforms from fibrous to coarse elongated recrystallized grain structure during homogenization at 550℃ for 4h. The grain in the interior tends to be equiaxed with the temperature. The primary particles are broken up after homogenization at 450℃ and 500℃ for 4h, respectively, and coarsened when temperature increases to 550℃. The evolution of dispersoids is controlled by nucleation and growth mechanisms at 450℃ and 500℃ for 4h, respectively, whereas the coarsening and dissolution are predominant mechanisms during homogenization at 550℃ for 4h. Many small size Zr-bearing dispersoids are obtained during homogenization at 500℃ for 4h.