In order to achieve the accurate pointing during the course of deep space optical communication link setting up, a scheme is proposed to acquire the extendbeacon for deep space optical communication system, which uses visual earth image as beacon, and stores a beacon image in aircraft as reference image. CCD is adopted to image the pointing area based on antenna scan pattern. The correlation coefficient of the detected image and reference image is calculated based on pixel scan pattern. The location where the correlation coefficient is maximum is found out after antenna scan, which can be regard as the location where the beacon image is acquired. Because of the rotation and scale invariance of FourierMellin transform, the effect from rotation and scale of image will be eliminated based on FourierMellin transform. 1000 random fields of view are created using MonteCarlo method, to simulate the progress of acquisition, and the result shows that the successful acquisition probability is 99.6% within 3σ, validating its feasibility.