Ducted fan UAVs possess significant advantages such as high payload capacity and enhanced safety. However, conventional ducted fan UAV control mechanisms are inherently underactuated, making precise control challenging, especially in confined spaces. Inspired by the fine adjustment behavior of fish gill flaps regulating water pressure differentials, this paper proposes a novel bio-mimetic gill side window sliding flow actuator. A dynamic model of this side window sliding flow actuator is established, and a heterogeneous actuator composite position control method based on side window sliding flow is de-signed. Comparative semi-physical simulation experiments are conducted be-tween the proposed method and traditional cascaded position control methods. The results indicate that the control method based on the biomimetic gill side window actuator accurately tracks actual position commands, improves over-shoot conditions, and flight experiments validate the advanced nature of this actuator and its control method.