Abstract: In spacecraft rendezvous and docking, a computer vision system is used as an accurate sensing device for estimating the three dimensional position and orientation of the spacecraft relative to a coordinate system fixed on a space station, providing feedback information needed for guidance and control loops. In this paper, the methods of the two dimensional image information sampled by computer vision system are studied for estimating the position and attitude of the spacecraft relative to the space station. Algorithm of fitting measured light line with light point is proposed in this paper, and the digital simulation results are also presented.