Abstract: The reasons of the magnification inconsistency for the framing system in the high-speed rotating mirror framing camera were analyzed theoretically. The correction method of transversal magnification for the framing system was introduced. Taking model FJZ-250 rotating mirror framing camera as an example, the magnification and correcting coefficient of each frame are presented. The measurement results indicate that the magnification inconsistency of the framing system is different significantly with the theoretically calculated value. The spatial test accuracy would be improved by processing the experimental negatives with the corrected coefficient.