Abstract: In order to maximizing performance of search and track systems using focal plane array detectors, special optical de-scanning techniques are adopted in this paper. Form and composition of de-scanning path of object and image are given, and features of different de-scanning technique such as parallel and converging de-scanning are analyzed. Optical problems in de-scanning process and relative solutions are also described. Viewpoint of maximum optical principle error of less than 1/3~1/4 pixel is also proposed.