Airborne area array whisk-broom imaging systems require a high enough overlap rate between frames to avoid missed scans caused by the control error of the line of sight (LOS) during the scanning process, which restricts the imaging system's adaptability under conditions of high speed height ratio, and limits the imaging swath of the system. This paper proposes a new method of LOS path planning model and overlap rate calculation. The scanning path of the LOS of the imaging system is optimal designed through the geometric analysis method of the image spherical projection, and based on the azimuth rotation angle of the image plane projection in the image sphere, a new model for overlap rate calculation is developed. Theoretical analysis and simulation experiments have verified that the stabilization accuracy of the LOS is increased from 2.93° to 0.15° when the lateral gaze imaging is performed at 40°, and the operation efficiency is increased by about 32% when the same speed height ratio and single-line 5-frame whisk-broom imaging are performed. The research work of this thesis is of great significance to promote the further development of airborne whisk-broom imaging technology toward the direction of wide field of view, high speed height ratio, and high resolution.