Abstract: In order to explore the application of 3D laser scanning technology in deformation monitoring of hydraulic tunnels, overcome the limitations of traditional methods in complex 3D spaces and improve monitoring accuracy and efficiency, this study took the Huangtan Tunnel of Qianming Reservoir Diversion Project in Jinyun County, Zhejiang Province as the research object. High-precision point cloud data from multiple periods were collected using 3D laser scanning technology. By analyzing cross-sectional center points and center lines, the tunnel's deformation characteristics were studied. Results showed that the absolute values of relative changes in the geometric centers of the two cross-sections in the horizontal and vertical directions did not exceed 1 mm; the absolute values of angular deviations between the tunnel center lines in each period and those in the first period were controlled within 10 arcsec, with corresponding displacement deviations of no more than 1 mm. This demonstrated that 3D laser scanning technology could provide large-scale, highprecision deformation monitoring for hydraulic tunnels, effectively overcoming the limitations of traditional methods and providing technical support for deformation monitoring of hydraulic tunnels.