Introducing laser scanning as a novel non-contact measurement technology known for its rapid speed and high preci- sion,commonly applied in surface damage detection.This paper presents an algorithm for detecting surface cracks on concrete prefabricated boX girders based on laser point cloud scanning.By analyzing height differences along scanning lines, the algo- rithm identifies crack locations and employs wavelet decomposition to enhance detection accuracy of mutation points.connect- ing these points across different scanning lines reveals the crack distribution.EXperimental results demonstrate the algorithm I s capability to accurately identify individual linear cracks on prefabricated boX girder surfaces, with optimal performance achieved using 4-layer wavelet decomposition with coif2 wavelet base for mutation point detection.