Abstract: In order to detect and evaluate the quality of tunnel excavation efficiently and accurately, taking the tunnel construction of Changlongshan Pumped Storage Power Station as an example, a method for overbreak and underbreak identification based on 3D laser scanning technology was proposed.The terrestrial scanner and portable 3D laser scanner (using simultaneous localization and mapping technology, also known as SLAM scanner) were used to carry out scanning modeling and overbreak and underbreak detection comparative analysis of tunnel surrounding rock, and the applicability, reliability and accuracy of SLAM scanner were evaluated.The results showed that the overbreak and underbreak identification method proposed in this paper was accurate and reliable, although the accuracy of the terrestrial laser scanner was relatively high, there were some problems such as local missing and uneven point cloud.The accuracy of the SLAM scanner can also meet the needs of engineering detection, the point cloud model is uniform and complete, but there are problems such as large target recognition error and cumulative error of the point cloud model.The research results can be used for reference in underground engineering excavation detection.