Abstract: As the core equipment of the power system,the insulation performance of the stator bar of a generator directly determines the operational reliability and safety of the unit.This article focuses on the non-overdue aging failure of a stator bar in an air-cooled generator,combining field test data,post-repair aging evaluation of the bar,and physical simulation of the failed bar.It systematically analyzes the causes of aging from aspects such as thermal aging,corona corrosion, mechanical vibration,and defects in the cooling system.Through targeted measures such as insulation treatment of the bar and optimization of the cooling system,equipment hazards are effectively eliminated.At the same time,a reliable long-term preventive maintenance strategy is proposed,providing a reference for the diagnosis and treatment of similar non-overdue aging issues in stator bars of air-cooled generators.