A method for structural damage detection includes following steps: utilizing a knocking device (112) to scan a surface of structure, and knocking with a knocking force possessing predetermined frequency band at the same time with the scanning; utilizing a sensor (114) to detect the response signal transferred to the knocking device (112) from the surface of the structure to-be-measured; transforming and processing the signal detected by the sensor (114) to acquire the signal spectrogram at each position of the surface of structure; intercepting the spectrogram envelope curve corresponding to the knocking force with the predetermined frequency band from the signal spectrogram; calculating damage indicating value at each position of the structure surface, the damage indicating value represent similarity degree between the spectrogram envelope curve at this position and the spectrogram envelope curve at other positions; and determining the position at which sudden transition happening to the damage indicating value occurring as the position with structural damage. A system for structural damage detection utilizing the method for structural damage detection and a device for structural damage detection used in the system are also disclosed.
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