In the process of generating horizontal nuclear line images, the nuclear lines on the horizontal images are not parallel to each other for general horizontal image pairs, that is, when the baseline is not parallel to the geodetic coordinate system. In order to obtain the correct and effective horizontal nuclear line image, the ground coordinate system is rotated to the horizontal direction of the baseline, and the nuclear line on the horizontal image is rearranged by a method similar to that of non-horizontal nuclear line rearrangement according to the coplanar conditions, so as to eliminate the problem that the nuclear line and the scan line are not parallel to the scanning line generated by the baseline non-level, reduce the calculation amount of subsequent work such as mapping and matching, and improve the operation speed. Finally, the relationship between the baseline inclination angle and the maximum angle between the nuclear lines on the horizontal image is given, and it is concluded that the non-horizontal nuclear line image should be used when the baseline inclination angle is large to ensure the quality of the nuclear line image.