The phase precipitation behavior of a new low-cobalt casting nickel-based superalloy was studied by thermodynamic calculation software JMatPro and differential scanning calorimetry (DSC), and compared with the microstructure and composition of the actual ingot. The results show that the as-cast microstructure of low-cobalt alloy mainly includes γ (matrix), γ′, carbides (MC, M6C) and γ+γ′ eutectic structure (volume fraction about 13.9%). Positive segregation of Ta and Hf occurrs during solidification. The DSC test shows that the initial melting point, final melting point and γ′ phase remelting temperature of the alloy are 1349.6℃, 1300.1℃ and 1272.1℃, respectively. Theoretical calculations are basically consistent with the experimental results. Thermodynamic calculation shows the increase of Al and W content can increase the precipitation amount and re-solubilization temperature of γ′ and M6C carbides, respectively. Hf and Ta elements may increase the liquid-precipitation tendency of MC carbides. The expected stress rupture property of the new low-cobalt alloys is better than that of existing commercial nickel-based polycrystalline casting superalloys.