The new thermally controlled solidification (TCS) process was deliberately modified to successfully produce equiaxed K4169 superalloy casting with little porosity. Thereafter, the influence of melt treatment (grain refiner and melt superheating temperature) on the microstructure and mechanical properties of K4169 superalloy are investigated. The results showed that: (1) New TCS process with low-temperature pouring, high-temperature filling and sequential solidification is proposed to simultaneously realize good forming and microstructure control for thin-walled castings. Characteristic structure castings of K4169 with thickness of 1.8mm is prepared. (2) Compound refiner of Co3FeNb2 and CrFeNb can obviously refine grain with TCS better than conventional process. Average grain size decreased from 3340μm to 126μm. At 650℃/620MPa, stress rupture life increased by 1.3 times to 201hr. (3) For TCS, melt superheating treatment can significantly refine grain to 89μm with melt superheat temperature 1680 ℃. At 650℃/620MPa, stress rupture life increased by 2 times to 242hr.