To complement the insufficient experimental study on the mechanical behavior of aluminum alloy at low temperature, tensile tests of Chinese structural aluminum alloy 6082-T6, 6N01-T6, 6061-T6, and 6061-T4 under constant low temperatures were carried out, and their mechanical properties including the ultimate tensile strength, nominal yield strength, elongation rate and section shrinkage were obtained at different temperatures that range from -120 to 20 ℃. It is found that material hardening of the aluminum alloy occurs at low temperatures, leading to the increase of the ultimate tensile strength and nominal yield strength. However, the change rule of the elongation rate and section shrinkage is not clear. The increasing factor formulae of the mechanical properties for the 4 kinds of aluminum alloy at low temperatures were derived through a numerical fitting method. Moreover, the fitting formulae were compared with the corresponding formula prescribed in American standard. The results demonstrate that the American standard method provides more conservative estimation