In view of the problem of removing local damaged paint layer on workpiece surface, it is an effective method to improve the cleaning quality and efficiency to implement the laser partition cleaning in high efficiency, and accurate identification of local damaged paint layer area contour is the premise of partition cleaning, therefore, a method of contour identification for laser partition cleaning based on machine vision is proposed. Aiming at the problem of difficulty to identify paint layer area contour caused by low camera exposure, an image enhancement method based on camera response model is adopted. Aiming at the problem of complex contour precise identification of paint layer area, a method of contour identification based on chroma coordinate value is proposed. In order to realize laser partition cleaning in high efficiency, a method of complex contour regularization of paint layer area based on minimum envelope rectangle is adopted, and a method of generation scanning path in variable distance is used. The experimental results show that this method achieves accurate identification of complex contour of paint layer area with low illumination, and improves the identification accuracy compared with the traditional iterative method.