Abstract: Two single crystal superalloys with nominal composition of Ni-9Ta-6Al-6W-4Co-2Cr-0.4Mo-xRe (x was 6.2, 6.8, respectively, mass fraction/%) were prepared. The effects of Re content on the microstructure and phase transition temperature of the as-cast alloys and on the microstructure and high-temperature stress rupture property of the heat-treated alloys were investigated. The results show that a slight increase of Re content resulted in the increase of the solidification segregation degree and the γ+γ' eutectic structure content in the as-cast alloys. The peak temperatures of rapid dissolution of eutectic structure increased during the solid solution process. The size of γ' phase in the heat-treated alloys decreased slightly and the topological close-packed phase formation increased in the stress rupture process. The minor increase of Re changed the element partitioning ratios of Re and Cr significantly, improved the solid solution strengthening effect and increased the high-temperature stress rupture properties of the alloys strikingly.