This paper shows some simulation analysis on stitching overlap threshold of strip images for multi-strip stitching model in agile remote sensing imaging. To realize the high spatial resolution and high time resolution at the same time, agile satellites have been used more frequently. Besides the maneuverability of satellite attitude adjustment, the mission planning is the key to the efficiency of high resolution optical imaging. Thus, our purpose is to find the suitable stitching overlap width between two adjacent strips. Lower threshold will sacrifice the stitching quality of remote sensing image, while higher threshold will cause an inefficient imaging mission. The mission model and geometric degradation model are proposed for multi-strip stitching imaging, and the criterion of overlap region width threshold is presented. We use scale-invariant feature transform (SIFT) detector for image registration and random sample consensus (RANSAC) to eliminate the outliers. Besides the root-mean-square error (RMSE) of feature points in overlap region, the RMSE of four corner points and all pixel points of overlap region are considered. When all these three RMSE are less than 1 pixel, the overlap threshold is confirmed.