The license image has geometric distortion because of several factors, such as camera location, camera distortion etc. It is difficult to recognize the license. To solve this problem, a series of image rectification procedure which utilize geometric rectification theory in vehicle license recognition system are pointed out. Firstly vehicle license was located and the edge detection and binary conversion were executed. Then real-time calibration was proceeded in which we used the calibration scheme to look for control point coordinate based on the Hough transform and image analysis method. Finally image correction was realized in geometrical transform and bilinear gray interpolation method. The experimental result affirms that this method is effective to the image of vehicle license.