In response to the problem of chatter and deformation during the precision machining process of the aircraft engine blisk, research on deformation control technology of the blisk was carried out, and a light-curing auxiliary support fixture based on reverse segmented machining was designed. Firstly, the effectiveness of reverse segmented machining in reducing deformation of the workpiece is explained based on the principle of piecewise rigidity during the machining process. Secondly, a three-section auxiliary support fixture was designed, including a compression block, a profiling block, and a fixing plate. The gap between the profiling block and the blade was filled with photosensitive resin to provide support for the machining of the blisk. And the support of the fixture was tested to verify the reliability of the fixture design. Finally, a validation experiment was conducted on reverse segmented machining using a blisk simulation component. The results show that the designed fixture reduced the machining error of the blade disc cross-section line, and the maximum tool deformation was reduced from 0.1 mm to 0.05 mm. This verified that the auxiliary fixture has a good deformation control effect on the blisk.