Unmanned aerial vehicles capable of hazardous terrain landing are desirable for intelligence collection. A crucial point is the landing gears autonomous adaptation to the rough surface, which is especially difficult in unknown and constrained environment. To enable this capability, this paper proposes a novel biomimetic system that ascertains terrain appearances like large obstacles and precipitous slope using a monocular camera and adjusts the mechatronics landing structure according to the terrain. A dynamic model including the ground effect is provided and a time-to-contact theory based backstepping nonlinear controller is designed to reject uncertainty disturbances as well as implement a bio-inspired guidance strategy for soft landing in hazardous terrain. The mechatronic architecture and cascade control structure using custom-built unmanned air vehicle platform are presented. Experimental results and video footage demonstrate this biomimetic approach efficiently controls a vehicle successfully landing in unknown and unstructured constrained environment.Index Terms-biomimetic design, autonomous landing, hazardous terrain adaptation, unmanned air vehicle (UAV)1083-4435 (c)