The merit of ducted fan UAV is addressed through the illustration of recent researches on it.The flight mechanism of ducted fan vehicles is probed,then a mathematical model of the vehicle is constructed based on the analysis of aerodynamic characters for all the components of the vehicle.The controller is designed and implemented in the flight testing.The results show that the ducted fan UAV has good character of hovering,and there is little cross-coupling between the roll and pitch channels in hovering and maneuvering at a small pitch angle,which can be ignored.