In order to cope with the difficulties in operating and maintaining old culverts in typical mountainous cities and the problems of easy formation of black and odorous water bodies, a culvert remediation project in the Yangtze River protection project is supported, and a multi-meaning comprehensive detection scheme with three-dimensional laser scanning technology is adopted as the core, and a special inspection of old culverts of about 1km is completed. Combined with the results of fine inspections of the ground community pipeline network, a systematic traceability analysis of the source of sewage in the concave is carried out. Through inspection, the precise plane position and internal elevation change characteristics of the culvert are clarified, the internal structural status of the culvert and its various defects are fully understood, and the source of sewage discharged into the culvert is determined; and the solid scientific basis and technical support for the subsequent formulation of efficient and precise measures for concealing rectification and pollution control are provided by the detailed data obtained.