This paper proposed the features of speed difference's change along with high pressure or low pressure rotor speed when twin-shaft engine was used in flight.Apoint of view was presented that speed difference is likely to arouse wake excitation between high pressure and low pressure rotor blade.The features of blade wake excitation caused by speed difference were briefly described through numerical examples.As compared with vane wake excitation

the blade wake excitation caused by speed difference features low stage vibration mode of high hazard exposure

wide resonance speed range and low excitation intensity.