A formation control algorithm based on distance constraints is proposed for multi-agent leader-follower strategy,and formation keeping and velocity tracking are realized simultaneously.The multi-agent system consists of a single leader and two followers.The single leader moves at a constant reference velocity, and the followers cannot measure the velocity of themselves or other agents.In order to track the speed of the single leader to achieve formation shape keeping,an adaptive control law is designed for the followers to estimate the velocity of the leader and keep each agent at the desired distance.Based on Lyapunov analysis and Barbalats lemma,the stability of the closed-loop system is proved,and the effectiveness of the proposed method is verified by simulation results.