0.020, 0.045 and 0.075 wt pct Zr were added to a Ni-base superalloy GH586 to investigate theirefFects on the microstructure and the short-term strengths at 850℃. The results showed thatproper Zr addition could improve the alloy tensile strength at 850℃ and short-term rupture life at850℃, 580 MPa. Zr exists in both γ’ phase and γ matrix, which caused Zr to distribute in graininstead of segregating in grain boundaries, therefore increased both of their lattice parametersbut decreased the mismatch between them. Meanwhile, it also increased the amount of grain-boundary carbides and decreased their size markedly. These contributed to the improvement ofshort-term rupture life. However, further addition of Zr resulted in forming Zr4C2S2, a plate-fike stable sulphurocarbides in grain boundaries, which decreased short-term strength at hightemperature, and led to a worse hot workability. According to the experimental results, theoptimum content of Zr should be 0.020 wt pct. 0.020, 0.045 and 0.075 wt pct Zr were added to a Ni-base superalloy GH586 to investigate theirefFects on the microstructure and the short-term strengths at 850 ° C. The results showed thatproper Zr addition could improve the alloy tensile strength at 850 ° C and short -term rupture life at850 ℃, 580 MPa. Zr exists in both γ ’phase and γ matrix, which caused Zr to distribute in graininstead of segregating in grain boundaries, therefore increased both mismatch between them. Meanwhile, it also contributed the amount of grain-boundary carbides and decreased their size markedly. These, contributed to the improvement of short-term rupture life. However, further addition of Zr resulted in forming Zr4C2S2, a plate-fike stable sulurocarbides in grain boundaries, where decreased short -term strength at hightemperature, and led to a worsehot workability. According to the experimental results, theoptimum content of Zr should be 0.020 wt pct.