Oversized titanium alloy intermediary casing casting is a key component of aero engines, with a complex structure and greatly varying wall thickness, which is the largest and heaviest intermediary casing casting in aviation engines at present. Traditional single-strand water inlet process schemes are prone to causing converging flows at multiple locations, such as the struts, splitter rings, and outer rings of the casing, leading to difficulties in mold filling and susceptibility to casting defects such as splashing and cold shuts. To address this, numerical simulations of the investment casting process for intermediate casing casting were conducted via ProCAST simulation software. Bottom-pour centrifugal casting was employed, with different numbers of water inlet strands and gate ratios being set. Changes in the fluid field and temperature field during the mold filling and solidification processes under different design schemes were studied and compared to select the optimal pouring process scheme. This aimed to achieve complete molding of the superlarge titanium alloy intermediate casing, paving the way for efficient aerospace engine production. The simulation results indicate that by utilizing the structural characteristics of the casting itself and adopting a four-strand water inlet process with additional slot gates, setting the ratio of sprue to runner to ingate as 1.0∶1.2∶2.5, the casting yield reaches 57%. Subsequent experimental validation of this process scheme yields castings that meet the relevant technical agreement specifications, with experimental results aligning with the simulation outcomes, thereby verifying the feasibility and accuracy of the simulation results.