In order to solve the problems of long coordination period and high collision accident rate of small underwater robot formation system, a leader-follower formation method based on binocular vision is proposed. The 3D relative positioning of the robot is realized by using the binocular vision system of the underwater spherical robot platform through the point matching algorithm. The control quantity calculated by the vision system is used as the input quantity of the robot motion control, and the safety threshold is set according to the motion performance of the robot to realize the underwater anti-collision formation of the robot.The formation experiment of 2 spherical robots is carried out. The results show that the method is effective.