The effects of alloying elements on the phase precipitation behavior of a new high-boron Ni-based superalloy were studied using JMatPro thermodynamic software and compared with the actual cast microstructure. The results indicate that the as-cast microstructure of the new high-boron Ni-based superalloy exhibits a typical dendritic morphology, mainly composed of γ, γ′, carbides, borides, and (γ+γ′) eutectic (about 15.5vol%). The segregation of Hf and Ta elements is obvious during the solidification process. Thermodynamic calculations indicate that Ti, Ta, Hf, Al, and B elements have great influence on the melting temperature of alloys. The initial precipitation temperature of γ′ phase and its precipitation amount at 900 ℃ are increased with the increase in Al content, while the influence of Ti element is relatively small. In addition, the Ta and Hf elements will promote the precipitation of MC-type carbide, and the influence of Cr element on the precipitation amount of M₂₃C₆ carbide is greater than that of M₆C carbide. The precipitation of borides is mainly influenced by Cr and W elements, while Mo element has a significant impact on the precipitation temperature of M₃B₂ borides. As the content of Co, Cr, W, and Mo elements increases, the precipitation amount and precipitation temperature of μ phase both show an increasing trend.