A series of laser surface remelting experiments of Al-1.1, 3.2 and 5.6 wt % Mn alloys has been conducted using a 5 kW CW CO2 laser, and the microstructures of samples have also been investigated. The experimental results show that no apparent eutectic growth appears in the whole growth rate range for Al-3.2 wt % Mn alloy under laser rapid solidification condition, and the microstructure grows in the form of α( Al) cell/dendrite. With the increase of growth rate, the microstructures of Al-5. 6wt% Mn alloy change from Al6Mn dendrite to α(Al) + Al6Mn eutectic, α(Al) cellular/dendrite and segregation-free solid solution. The critical rates of Al-1.1, 3.2 and 5.6 wt% Mn alloys to attain absolute stability are 44.1, 134.6 and 230.1 mm/s respectively, and a reasonable agreement has been found between the experimental results and those calculated according to Mullins-Sekerka’s theory. A series of laser surface remelting experiments of Al-1.1, 3.2 and 5.6 wt% Mn alloys has been conducted using a 5 kW CW CO2 laser, and the microstructures of samples have also been investigated. The experimental results show that no apparent eutectic growth appears in the whole growth rate range for Al-3.2 wt% Mn alloy under laser rapid solidification condition, and the microstructure grows in the form of α (Al) cell / dendrite. With the increase of growth rate, the microstructures of Al-5. The critical rates of Al-1.1, 3.2 and 5.6 wt% Mn alloys to attain absolute stability are 44.1, 134.6 and 230.1 mm / s respectively, and a reasonable agreement has been found between the experimental results and those calculated according to Mullins-Sekerka’s theory.