The invention relates to a method for positioning a region of interest. The method comprises the specific steps of: A, sticking a two-dimensional code, namely, a Marker label, at a determined position of an edge, of the region of interest; B, detecting the Marker label and positioning the ROI region of interest, wherein the step B specifically comprises the sub-steps of: (1) performing image graying; (2) performing image binaryzation; (3) detecting image profile; (4) searching possible Marker labels in the image; (5) detecting and decoding the possible Marker labels; (6) sieving the decoded possible marker labels and finding a correct Marker label; (7) positioning he region of interest. The Marker label are only black and white in color, so that the image after binaryzation is obvious, and the region of interest can be positioned rapidly and exactly, the image pre-treatment operation is simplified, the condition of light change can be adapted to, and the robustness is very strong.