Thin-wall frame titanium alloy castings are complex structural parts in the field of casting and are widely used in important parts of high-end equipment in the aviation and aerospace fields. There are widespread assembly requirements, and strict tolerances in terms of size, shape and position are needed. Owing to the complex structure, thin wall and uneven thickness of frame castings, shrinkage holes, deformation and other defects easily form during the casting process. Therefore, when determining the casting process, it is necessary to consider various factors and evaluate the feasibility of the process through casting simulation software. In this work, to address the issues of the large volume, large thickness ratio and complex structure of thin-walled frames, which are prone to casting defects such as shrinkage and porosity, thermal cracking and deformation during casting, two casting system schemes, namely, the top casting type and bottom casting type, were designed, and ProCAST simulation software was used to simulate the thermal field and stress field during the solidification process of two kinds of casting mold filling. The total shrinkage rate, residual stress and residual deformation of the frame parts in the casting solidification process were analysed, and the feasibility of the bottom filling pattern scheme was determined. A comparative analysis of the simulation results reveals that the titanium alloy frame produced by bottom casting is more stable than that produced by top casting, the total shrinkage rate is lower, and the effective stress between the rib plate and the wall plate of the casting body is significantly lower. The total deformation is reduced to less than 0.5 mm, and the deformation is mainly concentrated in the riser and the plane where the riser is located. The test results show that the process can effectively solve the problem of hot shrinkage holes in casting, and the forming quality, metallurgical quality and size control of the  casting can achieve the expected effects. Moreover, computer casting simulation technology can effectively guide the actual casting process, shorten the trial production cycle, reduce the production cost, and provide a reference for high-quality near-net investment casting of thin-wall frame titanium alloy castings.