Abstract: To overcome the blurred borders and poor distinction of the infrared images, an automatic object contour extraction method based on the Ostu threshold method and GVF Snake is proposed. The Ostu algorithm is adopted to segment the image. Then the extracted object contour is taken as an initial contour of Snake model for precise segmentation computation. After that, the initial contour is converged to the target borders precisely by utilizing the feature of GVF Snake. With GVF Snake model, the manual operation is reduced during the segmentation of complex images thanks to the advantages of the Ostu algorithm. Experiments show that such algorithm is fast in calculation, it can converge the contour to the target borders rapidly and track a target precisely, and it is immune to noise.