Based on thermodynamic calculation Pandat software and PanNi database, thermodynamic phase equilibrium calculation method was employed to investigate the effect of alloying composition on precipitation behavior of equilibrium phases in a low Re-containing nickel-based single crystal superalloy DD6. Results indicate that the equilibrium phases consist of γ, γ′, μ, MC and M₂₃C₆, and the calculated results are in excellent agreement with the experimental results. The Al, Ta and Nb content mainly control the mass fraction of γ′ precipitates. With increase of Al, Ta and Nb content, the mass fraction of γ′ precipitates is significantly enhanced, the solution temperature of γ′ precipitates is obviously increased, and the liquid starting and finishing solidification temperature is gradually decreased. The C content determines the precipitation amount of MC and M₂₃C₆. Increment of C content results in more precipitation of carbides. The precipitation of μ phase is predominantly influenced by Re, W, Mo and Cr. With the increase of Re, W, Mo and Cr content, the initial precipitation temperature of μ phase is significantly enhanced, the maximum precipitation amount of μ phase is obviously increased, and the precipitation temperature range of μ phase is markedly extended.