<p>Gas turbine blades are critical components that operate under extreme conditions, requiring precise manufacturing techniques to ensure their mechanical performance and durability. To improve the quality of gas turbine blades manufactured by investment casting, numerical simulations were employed to study the effects of shell preheating temperature and pouring temperature on the filling and solidification processes of casting. The simulation results indicate that both higher and lower shell temperatures adversely affect blade casting quality. When the shell preheating temperature is 1150°C or 1100°C, the castings exhibit significant localized temperature retention in the thick regions. At 1050°C, heat transfers from the thin-walled sections with higher temperature to the thick-walled sections with lower temperature, exacerbating the uneven cooling in the thick regions. At 1000°C, the cooling rate of the thick and thin regions is nearly the same, reducing internal casting defects. Additionally, the relationship between pouring temperature and filling status is not a simple linear one but is instead influenced by the interaction of multiple factors. The optimized preheating temperature of shell mold and pouring temperature are 1000°C and 1505°C, respectively, and the defects are largely eliminated.</p>