In order to eliminate the influence of rolling shutter on image quality in higher speed mapping by a CMOS airborne digital camera, the combination imaging mode of matrix array CMOS and high speed central mechanical shutter is emphatically studied based on CMOS imaging principle. The forward motion model and Signal-to-Noise Ratio (SNR) model of matrix array CMOS resolution imaging system based on the combination imaging mode are proposed and the existence of the corresponding range of exposure is proved under the condition of suitable forward motion and SNR of the airborne digital camera. A small-sized electric and exposure controlled accurately high speed central mechanical shutter is designed with the shortest exposure (1/2 000 s) and the highest efficiency (80%). Finally, the correctness of the right range of exposure is verified by the experimental results of the radiation calibration of an airborne digital camera based on a domestic CMOS image sensor. The experimental data indicates that the parameter proven of combination imaging mode is right and the camera's dynamic MTF at Nyquist frequency (91 lp/mm) is 0.21 which meets the practical application requirement.