To clarify the degradation law of the mechanical property of 6061-T4 aluminum alloy after elevated temperatures as recommended by the GB 50429—2007 code for design of aluminium structures, a total of thirty-eight 6061-T4 aluminum alloy specimens were designed, and the unidirectional loading tests and cyclic tensile loading tests at room temperature and elevated temperature were performed. The effects of cooling type and loading protocol on the failure characteristics, initial elastic modulus, strength, stress degradation, and energy dissipation were evaluated. The experimental results show that the yield platform and strain hardening behavior in the unidirectional cyclic tensile stress-strain curve of 6061-T4 aluminum alloy were not observed. When the heating temperature was in the range of 100~300 ℃, the surface of 6061-T4 aluminum alloy specimens became slightly darker but not significantly. The surface condition of the 6061-T4 aluminum alloy can not be used as an indicator to evaluate the damage degree after fire. The temperature had a slight effect on the initial modulus of 6061-T4 aluminum alloy, and the cooling method also slightly affected the mechanical property of 6061-T4 aluminum alloy. When the temperature was below 200 ℃, the temperature did not have a significant effect on the strength of the aluminum alloy. When the temperature was above 200 ℃, the strength of 6061-T4 aluminum alloy exhibited a significant decreasing trend with the increase in temperature. During unidirectional cyclic tensile tests at room temperature, the yield strain of aluminum alloy specimens was slightly lower than that of unidirectional loaded specimens. Due to the plastic accumulation damage during the cyclic tensile process, the ductility of the specimens deteriorated under unidirectional cyclic loading. With the continuous increase in temperature, the yield of the specimens tended to occur earlier, and the deformation capacity changed from worse to better. The energy dissipation capacity of 6061-T4 aluminum alloy gradually decreased with the increase of temperature, and the cumulative energy was positively correlated to aluminum alloy strength and cycle number.