In order to realize auto-alignment of terminal in ground laser communication simulation experiment, a precollimation method based on image recognition is proposed. First, indication cursor are extracted and reference cursor according to the color character of image. On the basis of the size of scale facula, the method establishes proportion relation between image and real object is built, and then the radius of target circle is estimated. Then based on Hough transform, the algorithm finds the centre of communication terminal caliber in the picture and calculates compensation angle between the centre and indication cursor. by sending the compensation angle to motion control card, it would make laser directly collimate to the terminal. At last, starting rose scanning and the process is terminated until capturing beacon light. Experimental results indicate that this method can detect the target exactly, and the calculation time is 0.94 s. It has perfect anti-jamming character. The method satisfies the requirements of auto-recognition and rapid collimation between two communication terminal.