The microstructural evolution including γ′ phase, carbide and Topologically Close-Packed (TCP) Phase of GTD111 and designed alloy WZ-D2 has been researched in directional solidification condition, heat treatment condition and ruptured at 980 ℃/190 MPa condition. The effects of these microstructural evolution on stress rupture property have also been studied. The size and volume fractions of eutectic phase in WZ-D2 are both significantly less than that in GTD111. The γ′ phase area fraction of WZ-D2 is apparently more than that of GTD111 after heat treatment, and the γ′ phase cubic degree of WZ-D2 is slightly higher than GTD111. The morphology of MC carbides in GTD111 is mostly presented as Chinese characters and is more unstable. The stress rupture lives of GTD111are obviously shorter than that of WZ-D2 when the work temperature is above 900 ℃, which is closely related to the difference in quantity and size of eutectic phase, the morphology and decomposition of MC carbide, and the evolution of γ′ phase in the two alloys.