To segment objects with abrupt change surface positioned at different depth, this paper presented a flexible technique for 3D depth segmentation. The system consisted of one projector, one camera, and the objects for segmentation. The first step was to establish the system for segmentation. The second step was to cast the phase-shifted gratings onto the object surface. The gratings, which were modulated by the 3D information of the objects, were then captured by the camera and sent to the computer for further processing. The wrapped phase sequence could then be calculated by changing the sequence of the phase-shifted patterns and using the least squares algorithm. By applying the neighbor pixel difference algorithm to the wrapped phase maps, the edges for segmentation could be retrieved further. Finally, these edges could be optimized and sent for segmentation. The simulation result shows that the method can effectively segment the complex objects with size 900 × 900 pixels, with the corresponding error reaching only two pixels. The experimental result shows that the approach can segment objects with similar color precisely. The proposed method has the advantages of low cost, high precision, and can perform the task of 3D depth segmentation.