Visual navigation method is an effective method for the autonomous landing of Unmanned Aerial Vehicle (UAV).This paper designs a landmark that consists of a ring and a circle made up of three primary colours, and a method for estimating the pose and position of UAVs based on the landmark is presented.The method first determines the target area through the detection of the outer ring, and then estimates the position and attitude parameters of the UAV relative to the platform according to the boundary lines of the internal tricolor circle and different color regions.Simulation experiments are conducted to the UAV at different heights.The results clearly show that the method can accurately determine the position and pose parameters of UAV relative to the landing pad, and can meet the requirement of real-time position and pose parameters measurement when UAV is landing.