Method of detecting and marking defect

A method of detecting and marking defect is provided. A detecting and marking system applied to this method controls a 2D camera module to shoot the difference regions of a test object for obtaining a detection 2D image of each region, executes a defect-detecting process on each detection 2D image for determining whether there is any defect in any region, controls a 3D camera module to shoot the region if there is the defect in the region for obtaining appearance 3D data of the region, measures a 3D position of the defect according to the appearance 3D data, and controls a marking module to mark the defect at the 3D position.