This study focuses on the problem of cracks generated during freeze-drying in the integrated ceramic casting mold of large-sized hollow turbine blade, and studies the stress distribution law of the casting mold. A theoretical model of stress generated by mold shrinkage obstruction was established through finite element simulation. Effects of various freeze-drying shrinkage rates, mold wall thicknesses, and curvatures on mold freeze-drying stress were analyzed. Structural optimization was carried out on trailing edge of the mold using variable wall thickness. It is found that during the freeze-drying process of integrated casting, the stress increases linearly with increase of shrinkage rate, and the stress is the highest at the position with the maximum curvature of the mold trailing edge. By increasing wall thickness at the trailing edge, bending strength of the mold during freeze-drying process is enhanced. When sample thickness increases from 4 mm to 7 mm, average strength of the base substrate increases from 8.32 MPa to 11.81 MPa. The integrated mold with structural integrity is successfully manufactured and verified by casting in this study, stress distribution law of ceramic casting mold and various wall thickness of trailing edge are obtained and proposed, which help to solve the issue of cracks generated during freeze drying for integrated ceramic casting mold.