The paper introduces the conception of machine vision,discusses the application of the airborne monocular camera machine vision in the system of auto landing on deck of UAV.On the basis of quick detection of the front naval ship and beforehand calibration of camera,using the theories and methods of machine vision,the intrinsic parameters of camera and projective geometry,the distance between the UAV and the naval ship is reckoned in the paper.Finlly it prospects the development and applications of machine vision.