In this article, the formation tracking control problem with prescribed performance is studied for multiple unmanned aerial vehicles whose disturbance is bounded with unknown boundary. Different from most existing works where prescribed performance control is realized based on error transformation, a new prescribed performance function-based adaptive strategy is proposed to guarantee both transient and steady state performance, which simplifies the design procedure. Furthermore, the proposed adaptive distributed sliding mode controller is of low complex and easily implementable, without utilizing the information of the external disturbance or any approximating structures to acquire such knowledge. Additionally, collision avoidance constraints among neighbors can be satisfied through appropriately designed performance bounds. Simulation verification also confirms the effectiveness of the proposed approach.