This paper considers the problems of target tracking and obstacle avoidance for multi-agent systems.To solve the problem that multiple agents cannot effectively track the target while avoiding obstacle in dynamic environment,a novel control algorithm based on potential function and behavior rules is proposed.Meanwhile,the interactions among agents are also considered.According to the state whether an agent is within the area of its neighbors influence,two kinds of potential functions are presented.Meanwhile,the distributed control input of each agent is determined by relative velocities as well as relative positions among agents,target and obstacle.The maximum linear speed of the agents is also discussed.Finally,simulation studies are given to demonstrate the performance of the proposed algorithm.