For the problem of unmanned aerial vehicle(UAV) swarm transformation and formation control in complex environments, the UAV swarm formation transformation strategy is proposed to suppress external interference, and a formation sliding mode control method is designed. Firstly, considering the existence of multiple leaders in the UAV swarm, a “double layer leader-follower" UAV swarm cooperative formation transformation control strategy is proposed to achieve formation transformation in complex environments. Secondly, based on graph theory, consensus theory and sliding mode control theory, a time-varying follower formation control law is designed for the UAV swarm under the condition of external disturbances, which can achieve continuous changes of UAV formation geometry parameters and geometric patterns. Thirdly, the stability of the formation transformation of the multi-leader UAV system under the disturbance condition is demonstrated using the Lyapunov function method. Finally, numerical simulations are used to verify the effectiveness of the formation transformation control method.