Abstract: During the pressure-regulating precision casting of nickel-based superalloys, problems such as shrinkage porosity and coarse microstructure are prone to occur. The effects of shell-mold preheating temperature and holding pressure on the interfacial heat transfer behavior, solidification defects, microstructure, and mechanical properties of castings were systematically investigated. Taking 10 mm thick plate castings of K439B alloy as the research object, five groups of single- factor controlled experiments were designed with shell-mold preheating temperatures of 800 ℃-1000 ℃ and holding pressures of 70 kPa-110 kPa. The interfacial heat transfer coefficient was inversely determined using B-type thermocouple temperature measurement combined with ProCAST numerical simulation, and the intrinsic correlation mechanism among process parameters, interfacial heat transfer, solidification behavior, and microstructure properties were revealed. The results show that reducing the shell-mold preheating temperature significantly increases the interfacial heat transfer coefficient above the solidus temperature. Under the 800 ℃ process, the cooling rate is 132.5% higher than that under 1000 ℃, the porosity decreases from 3.62% to 0.88%, and the secondary dendrite arm spacing, grain size, and MC carbides are all significantly refined. The tensile strength is improved by 28.46%, and the elongation increases from 1.7% to 8.0%. Increasing the holding pressure also enhances the interfacial heat transfer capability. Under the 110 kPa process, the cooling rate is 40% higher than that under 70 kPa, the porosity decreases to 1.22%, and the yield strength and tensile strength increase by 10.04% and 18.35%, respectively. This study elucidates the complete chain of how pressure-regulating precision casting process parameters affect casting quality by regulating interfacial heat transfer behavior, providing a theoretical basis for optimizing the pressure-regulating precision casting process of nickel-based superalloys.