The currently existing contour extraction algorithm extracting the corneal contour of corneal visualization scheimpflug technology (Corvis ST) image,due to the close gray distribution of the cornea edge local image,the corneal contour extracted generally is incomplete or corneal contour edges extracted appear small extenuation. This will destroy the integrity of the corneal contour,and the extracted corneal contour is seriously inconsistent with the actual original corneal image. In this paper,a high-efficient image processing method based on OTSU algorithm is designed for contour extraction of corneal images collected by the Corvis ST.Firstly,the corneal image is processed by impurity removal, gray scale and image denoising to reduce the amount of image computation and digital image noise interference.Secondly,the image is segmented based on OTSU algorithm,and mathematical morphology operation is added on the basis to smooth the image boundary and fill small "holes".Finally,Canny edge detection algorithm is used to extract corneal contour in the image,achieving the purpose of extracting high integrity corneal contour. On the same image data set,the contour extraction algorithm (B-OTSU algorithm) designed in the latest button contour defect detection system is compared with this algorithm in the experiment.The experimental results show that from the perspective of contour integrity and accuracy,the corneal contours extracted by the proposed method are obviously superior to the corneal contours extracted by the B-OTSU algorithm in the button contour defect detection system.