Abstract: As a typical structure of the prefabricated shear wall buildings, the bottom joint with characteristic of narrow space is prone to hidden defects such as void and leakiness during the process of construction. To achieve effective detection of construction defects in the bottom joint of the prefabricated shear wall structure, both numerical simulation and experimental methods were used to study different detection methods based on the ultrasonic longitudinal wave. Theoretical analysis of the recognition capability of single-side testing method and penetration testing method for different defects in the bottom joints was conducted to select appropriate testing methods and parameters for the rapid detection of construction defects, then the laboratory specimen testing and engineering application were adopted to verify the theoretical analysis results. The results showed that both the single-side testing method and penetration testing method could effectively identify the construction defects in the bottom joints. The variation amplitude of the direct wave of longitudinal wave at the defect location was larger than the corresponding value of the propagation speed, therefore, the signal amplitude of the direct wave was preferred as the primary indicator for judging the defect. The single-side testing method is suitable for the rapid detection of the entire bottom joint, while the penetration testing method is referred to spot-check. During the field detection, advantages of the two testing methods can be integrated to achieve rapid and refined identification of defects in the bottom joints.