In order to extract the road traffic flow information using UAV images, it is necessary to calculate the location of the road area and generate the road template for road tracking. Real-time calculation requires automated seed points extraction for identifying road and generating tracing template. A one-dimensional unmarked watershed segmentation method is proposed, which needs to calculate using the simple image feature, and don't need manual seed points mark. Firstly, by recognizing sectional extremum in the profile of source image road, the valley regions are extracted between extremums and the similarity is calculated through the region. Then, combine the nearly similar regions, get the segmentation results. Secondly, rank the segmentation regions, search radiology in the ranked regions, and identify the road area and calculate road track template. Experimental results show that the method need less manual intervention and more efficiency than the Canny edge extraction and Hough line extraction under the same conditions. By fitting the road edge points by the least squares method to get the direction of the road, the calculation of road direction is accurate, and the calculated tracking template is consistent with the actual that.