Models of intact and defective anchor bolts of different lengths are tested to study the rules of acoustic wave propagation in the anchoring body when sonic reflection method is used to detect the anchorage quality. For the intact bolts, the response wave gets more regular with the increase of the bolt length; at the meantime, the amplitude of bottom reflected wave reduces gradually and the reflected wave decays more severely. For the defective anchor bolts, the wave at defective location is distorted with an irregular wave attenuating slowly or attenuating after intermittent increase. The testing curves of acceleration response signal at bolt head exhibit different waveform characteristics when the bolt length or defective location is different. The consolidation wave velocity of bolt anchoring system reduces slightly with the increase of bolt length, and increases slightly along with the increase of defect size both within the range of 4200 m /s to 4400m /s.