The invention discloses a method for calculating shot blasting deformation of a large-size arc-shaped part. The method specifically comprises the following steps: S1, performing test detection; S2, performing finite element multi-projectile simulation; S3, establishing an induced stress library; S4, calculating shot blasting deformation of the large-size thin-wall arc-shaped part; specifically, the shot blasting deformation of the thin-wall arc-shaped part is predicted by establishing a theoretical model. According to the method, the deformation of the large-size part under different shot blasting parameters can be efficiently, rapidly and accurately predicted before the shot blasting process treatment, and references and bases are provided for making and optimizing the shot blasting scheme.