For the formation tracking problem for swarm systems, an optimal control method with linear quadratic regulator performance index was put forward.Establish the mathematical description of the formation tracking problem and design a formation tracking control protocol. Necessary and sufficient conditions for swarm systems with formation tracking were obtained and the stability of the system was analysed by using the second method of Lyapunov.Topology conditions of the control protocol which can minimize linear quadratic regulator performance index were obtained and the formation tracking algorithm was designed.A numerical simulation was provided to illustrate the effectiveness of the control method.