In response to the technical requirements for drone swarm navigation in complex environments, this paper presents various multi-drone methods for group formation control, trajectory planning, and virtual conduit control. The paper describes formation control algorithms, cooperative path planning, safe flight corridors, MPC, virtual flight conduits, and other trajectory planning optimization algorithms in separate chapters. Additionally, the latest applications and technological advancements of multi-drone navigation methods in complex environments are discussed, highlighting popular aircraft cluster motion planning approaches. Furthermore, a comparative analysis of the advantages and challenges of different methods is provided, along with an overview of future directions in this field.