Abstract: Image sequence acquired by digital cameras has the advantages of high-overlap and redundancy of observations, which makes it more and more popular in 3D reconstruction. Precision of relative orientation and forward intersection with high overlapping image sequence is analyzed. The higher the overlap is, the better the result of relative orientation is. The more images are used, and the bigger the intersection angle is, the higher the precision of forward intersection is. In practice, images with 80 % overlap are optimal for 3D reconstruction and other applications.