Abstract: The ability to search in accordance with standard graphics is one of the key capabilities of IR seeker, which can make up small filed of view and improve the ability of target acquisition. For roll-pitch infrared platform, the searching graphic distortion was analyzed by using the common method that the two orthogonal axes scan in turn. The standard mouth searching was carried out by a new proposed segmented scan method, which a recursively solving spherical arc line constraint equation based on quaternion was used. This segmented method was constrained less and the algorithm was small amount of calculation. It was a more efficient solution to solve the approximation search problem. A virtual simulation system was built using the MATLAB ToolBox and the validity of the segmented scanning method was also proved. This method can not only implement the standard mouth searching pattern at any position in the front hemisphere scene, but also be used for any arbitrary shape search pattern for the analogous seeker.