In order to study the effect of Ru on the microstructure stability of high generation single-crystal superalloys, two single-crystal superalloys D1 and D2 containing 6wt.%Ru and 4.5wt.%Ru respectively were prepared. After complete heat treatment, they were long-term aged at 980℃ and 1160℃ for 200h. The alloy microstructure of different scales, compositions of topologically close-packed (TCP) phase and TCP crystal structures were detected. Results show that after long-term aging at 980℃ for 200h, the precipitation of TCP in D1 alloy containing more Ru is significantly higher than that in D2 alloy; after long-term aging at 1160 ℃ for 200h, no TCP phase is observed in D1 alloy, while a small amount of TCP phase is observed in D2 alloy; the TCP phases in both alloys are of the same type, and Ru is one of the main forming elements. The experimental results are analyzed combining with d-electrons concept and thermodynamic calculation. It is shown that the influence of Ru on the TCP precipitation of single crystal superalloys has two sides. On the one hand, adding Ru can increase the d-electron energy level of single crystal superalloys, which increase the TCP precipitation tendency. On the other hand, the increase of Ru content can reduce the segregation of refractory elements in γ phase, thus reducing the amount of TCP phase precipitation caused by the supersaturation of refractory elements. At different temperatures, the main influencing factors are different.