Effect of cryogenic treatments on mechanical properties of 2A11 aluminum alloy were studied. Cryogenic box with program control and electrical resistance furnace were employed to perform cryogenic treatment processes as well as heat treatment processes. Impact tester, tensile tester, three-coordinates measuring machine, high precision caliper and standard metallography were used to carry out tests. The influences of different process parameters on mechanical properties of 2A11 aluminum alloy were compared, and the results showed that cryogenic treatment could improve mechanical properties of 2A11 aluminum alloy. The dimensional stability increases after cryogenic treatment once, and increases further after cryogenic treatment again.