Abstract: In this paper, a novel edge detection method based on intuitionistic fuzzy set(IFS)for hardwood seedlings leaves is proposed to accurately segment the leaves from images in complex background. Firstly, 3×3 templates of the x-direction, y direction, the direction of 45° and 135° were utilized to cluster the R, G, and B gray image respectively. Secondly, the maximum variance method was proposed to extract the fuzzy clustering image threshold. Finally, image edge was detected according to the threshold, where a clear boundary was obtained. Proposed method performed better than classical edge detection methods of differential operator. Experiments for kinds of hardwood seedlings were carried out, and the results indicated that the proposed method was effectiveness to detect the leaf edge, especially for the overlap region.