<p>A novel determination for optimal heat treatment for Ni-based single-crystal superalloys was proposed in the present work to optimize the strengthening effects of refractory elements. The relationship between the thermal stability of γ′ phase with the first aging temperature and high-temperature creep life was established. With the assistance of redissolution experiments, it was found that the thermal stability of γ′ phase showed a parabolic relationship with the aging heat treatment temperature, and the same tendency appeared for the creep life of specimens with different heat treatments. Generally, the stability of γ′ phase is closely related to the contents of Al, Ti, and Ta. The higher aging temperature would increase the γ′-forming elements content in γ′ phase; once the aging temperature is hyper-high, the enhanced solubility of γ matrix could trigger the redissolution of the primary γ′ phase, which decreases the γ′-forming elements content in γ′ phase. This study verified that the redissolution experiments are productive for the determination of heat treatment by evaluating the γ′ stability, which could guide future application of Ni-based single-crystal superalloys.</p>