In this research, the effects of solution time and long-term aging on microstructure evolution and mechanical properties of a traditional nickel-based single crystal superalloy under different heat treatment conditions were studied. The obtained results demonstrate that the best heat treatment regime is “1310℃/4h (AC)+1130℃/4h (AC)+899℃/16h (AC)”. After the solution treatment, the participating of adverse phase of TCP has been avoided to obtain the preferable microstructure with small size and a high degree of cubic of strengtheningγ′phase. The difference in creep rupture life and percentage of elongation is slight under different heat treatment regimes. During the deformation, the brittle TCP phase was broken first, demonstrating that it is not the crack initiation. However, the weak carbide/matrix interface in inter-dendrites is the source of the crack.