In order to extract center and radius of target in the image, a method based on global information of target is proposed. Hough Transform (HT) for circle detection is provided as a preprocessing procedure for target detection, results of HT are used as reference for segmenting the region for target parameters determination. Region contains target found by HT is called region of interest (ROI), and square regions on the target and centroids of square regions are extracted in further step. Centroids of square regions are used to fit circle for determination of precise position of center and radius of target. According to center and radius of target, other regions on the target are detected, and parameters of these regions are deduced. Correspondences between parameters extracted from the image and model target are calculated. Experiments operated in laboratory show that position precision of centroids of regions in ROI is 0.09 pixel, and experiments outside of laboratory show that the precision is 0.12 pixel. Complexity is simplified and position precision is improved in accordance to previous image when sequence images are under processing.