The dynamic strain monitoring technique for the rim of cylinder gear was studied based on the principle of dynamic stress measurement for high speed rotor structure. The dynamic stress data of the gear was measured by using the test system designed specifically for the accessory gearbox in a certain aero engine. The analysis results showed that the gear had one order and three order vibration modes based on actual conditions

and the maximum frequency amplitude was 21MPa. The dynamic stress of the rim of cylinder gear with improved design was decreased by 43.8% compared with that before improvement.