Aiming at the formation control problem of distributed swarm systems, a distributed formation control method under the condition of directed topology is proposed.Firstly,by introducing auxiliary functions into the control protocol and using variable substitution, the formation control problem is simplified to the stability problem of the autonomous system, which simplifies the complex control problem.Secondly, the control gain matrix is designed by solving linear matrix inequality, which is simple in form and low in complexity.Then the stability of the system is analyzed by Lyapunov method.The simulation results show that the multi-UAV system can effectively realize formation tracking control under the distributed control protocol.