Abstract: Through the implementation of a series of software simulations, experimental detections, and engineering trial productions, a systematic investigation was carried out regarding the challenges in achieving grain homogenization for 30Cr2Ni4MoV special-shaped flywheel forgings. Specifically, it was difficult to meet the requirement of the central ultimate sensitivity of Φ1.6 mm equivalent for the forgings after quenching and tempering. During the forming process, the upsetting with a large upsetting ratio leads to an unfavorable characteristic. In the area near the 3 meter diameter of the forging shaft, a large - scale region with difficult deformation appears. As a result, the inheritance of the material microstructure is severe, and the grain size cannot be effectively refined through multiple normalizing processes. By conducting experiments, the nose temperature of the TTT transformation of the material was obtained. Based on this, an isothermal transformation process was designed and applied to the engineering practice of forgings. This approach aims to enhance both the effectiveness of grain refinement through isothermal transformation and the economic efficiency of flywheel forgings.