Abstract: In order to solve the common problems of wire rod heating, insulation attenuation, ozone, and structural looseness in the stator of old hydroelectric generators due to long-term service, this study conducted research on the optimization and renovation technology of hydroelectric generator stator. The article first selects polyester glass sintered enameled copper flat wire, reduces the insulation thickness to expand the conductor cross-sectional area, and then optimizes the stator bar structure. Then upgrade resistance brazing to medium frequency induction brazing, which can reduce the number of welds and improve joint stability. By using epoxy glass cloth board to thicken the insulation layer and adding wear-resistant protective cover, the through-hole screw insulation system is reconstructed. Finally, design an "L" - shaped low carbon steel limit block to achieve axial limit of the pigeon tail reinforcement through welding. The optimization and renovation technology scheme was applied to the actual unit renovation. The 72 h trial operation results showed that the electrical parameters of the renovated unit were more reasonable, the stator and bearing temperature were significantly reduced, and the structural stability was greatly improved, fully meeting the requirements of continuous operation at rated power and long-term reliability.