Abstract: For quadrotor unmanned air vehicles (UAVs) flight control problem, a robust controller design approach is presented. The controller consists of two parts: an inner-loop attitude controller and an outer-loop position controller. The attitude controller is designed with robust control based on signal compensation. The position controller is realized with classical PD method. It is applied to a quadrotor UAV developed in our laboratory to realize indoor hovering. Experimental results demonstrate the effectiveness of this control approach.