In this paper,based on the binocular stereo vision sensor 3D measurement model and the principle of coordinate transformation of space and adopting the least square redundant algorithm,the basic principle of the measuremant of the space 3D point coordinate by the two-camera is discussed.The non-linear measurement equation of the visual measuring system is establishea.Through experiment,the feasibility of the Two-light pen-camera visual 3D coordinate measuring system is proved.