Nickel-base superalloys for heavy-duty gas turbines usually have a high Cr content, but the high Cr content makes it difficult to optimize the composition design of the alloy. In particular, in order to avoid the precipitation of harmful TCP phases, the content of solution-strengthening elements W and Mo is limited. In this paper, the effects of W and Mo content changes on the precipitation of nickel-based oriented superalloy DZ409 at 900°C and 1000 h in the γ/γ′ two-phase state and TCP phase were studied by using complex multi-component diffusion multi-joint technology. The experimental results show that when the Mo content remains unchanged, the volume fraction of the γ′ phase remains basically unchanged when the Mo content increases from 0wt.% to 4.6wt.%, and the size of the γ′ phase decreases and the morphology changes from spherical to square. The W content continued to increase, and σ and P phases were precipitated in the alloy. When the Mo content increased from 1.4wt.% to 1.6wt.%, and the W content decreased from 4wt.% to 3.3wt.%, the volume fraction of the γ′ phase increased slightly, the size of the γ′ phase decreased and the morphology remained square. After the Mo content exceeded 1.6wt.%, the σ phase and P phase were precipitated in the alloy. According to the APT tip reconstruction diagram and the ion distribution map of each major element, it can be seen that the increase of W content will promote the precipitation of TCP phase, and the addition of Mo while reducing W will also promote the precipitation of TCP phase of the alloy, mainly because the enrichment of W, Cr and other elements in the γ matrix makes the total amount of refractory elements in the γ phase exceed the solid solution limit of γ matrix. In this paper, the method guidance and data support for the composition optimization of nickel-based oriented superalloy DZ409 for gas turbines are provided.