Three circle centers are taken as chief mark of the target-plane. These circles are taken as auxiliary mark. The circle center is marked by the intersection of two lines. The diameter parallel to the image-plane is taken as characteristic diameter,by which the depth information for the target plane can be got from elliptic figures on the image-plane easily,so the solution of the inverse-perspective-transformation can be made simple and accurate. By designing a sub-pixel processing,circler-centre-image position and characteristic diameter image length can be got exactly. An algorithm was designed to calculate circle centre position. Then plane formula of the target plane can be got. The rudder’s angular displacement can be expressed by the target’s angular displacement. The computer simulating test indicates that measurement error for circle center image position within 0.02 pixels and measurement error for angular displacement within 0.005°. The measurement error caused by the target plane deviation from the direction parallel with the rudder-axis can be corrected in time. By this method,the angular displacement of aileron,flop,elevator and rudder of the airplane may be calibrated.