A novel nickel-based single crystal superalloys containing 0.4% Mo - 6.4% Re, 2.8% Mo - 6.4% Re and 0.4% Mo - 6.8% Re, respectively, in nominal composition was prepared. The element concentrations of alloys after SHT were measured, γ′ phase evolution and topological close-packed phase (TCP) precipitation of the alloys thermal exposed at 1100℃ up to 1 000 h were analyzed. The slight increment of Re and the increase of Mo content obviously facilitated the segregation of elements between dendrite and interdendrite, and between γ and γ′ phase. The coarsening rate of the γ′ phase during thermal exposure was reduced due to the segregation of low-diffusion elements such as Re in the dendrite core and the γ phase. The slight increase of Re promoted the precipitation of P phase but inhibited the growth rate of P phase, because the nucleation of the P phase was promoted by the segregation of the P phase forming elements Re, W and Ru in the dendrite core. However, the growth rate was inhibited because of contaction and intersection of precipitated P in large amount. The large increase of Mo content made both μ phase and P phase exist during the long-term thermal exposure at 1100 ℃. The μ phase was preferentially precipitated with a large number and a large size, while the precipitation of the P phase was delayed with smaller number and size. Mo promotes the segregation of the main constituent elements of μ phase, Re, W, and Mo in the dendrite core, especially the increase of Mo content, which promotes the preferential precipitation of μ phase. With the consumption of μ phase forming elements, and the presence of P phase is more stable at 1100 °C, P phase precipitates subsequently.