Share-beam multi-channel laser ranging sensor is usually used to detect rut depth by measuring several discrete points of the road which are used to form section information. The great transverse sampling distance causes large measurement error. A new laser method to detect rut depth is introduced; it measures three-dimensional (3D) section by integrating line laser sensor with 3D camera, which is used to resolve rut depth. 3D camera collects light image in the form of line structure projected on the road by laser at a certain angle, obtains 3D section data and rejects the abnormal value by the Pauta criterion. After rotating, translating and pattern recognition, left and right wheels mark and maximum rut depth are achieved. A case study shows that repeatability and correlation of data are over 98%. Compared with traditional methods, the proposed method has the better performance of short sampling distance, high accuracy, low cost, versatility and widely promotional value.