This study aims to verify the effect of image-distortion correction on the edge-field-of-view scanning direction in the case of zoom-scanning wide-swath imaging and to simplify the scanning mirror control. First, the nonlinear relationship between the scanning speed of a scanning mirror and the imaging angle of view during zoom imaging is analyzed. With respect to the problem of low stability and the difficulty of realizing control of the variable-speed scanning of the mirror, uniform angular-velocity scanning with a scanning mirror combined with a variable-frame-rate zoom-imaging detector is proposed based on the analysis and realization of a variable-frame-rate detector. Based on the experimental system, the relationship between the focal length of the optical system, the real-time frame rate of the camera, and the imaging field angles at the time of the uniform angular velocity scanning are determined in order to achieve variable-frame-rate zoom scanning imaging. Finally, a wide-swath long-wave infrared (IR) zoom experiment system based on mirror-scanning imaging is constructed using the pre-existing continuous zooming long-wave IR optical system, and the system is used for imaging verification. The results show that by employing a variable frame rate combined with zoom imaging, the image distortion of the edge-field-of-view can be effectively suppressed in the scan direction in wide-swath imaging. The variable frame rate imaging method simplifies the scan-mirror scanning in zoom scanning, and it is confirmed that the zoom-scanning method is able to eliminate the image distortion.