The invention relates to a three-dimensional dental model segmentation method for computer-aided stealth orthodontics, which comprises the following steps: step 1, reading a triangular mesh dental model; step 2, simplifying the model; step 3, marking a tooth seed point and a dental see point; step 4, setting a threshold value, and forming a tooth contour line through the set characteristic regionand the diffusion operation; step 5, repeating that step 4 until the diffusion of all tooth seed point is finished; step 6, carrying out tooth side bypass; step 7, obtaining a hole mesh model; step 8:integrating the step 4 and the step 7 to obtain the final single tooth model. There are few interactions and simple interactions, even if there are some errors, the results of tooth segmentation arenot impacted. Through repair of the holes between teeth, the shape of the teeth can be automatically restored, so that a single tooth with lateral shape can be separated, the boundary of the segmentedtooth is clear and accurate, andfurther treatment is convenient in the later stage.