To eliminate the influence of Rolling Shutter(RS) on imaging quality in higher speed imaging by a CMOS (Complementary Metal-Oxide Semiconductor) aerial camera, a mathematical model to calculate the RS effect at arbitrary gesture angles was built . The CMOS imaging principle was analyzed, and each pixel velocity of CMOS array was derived from coordinate transformations. After analysis of the working principle of the RS, the analytical equation of the RS effect was deduced. The Monte Carlo statistical method was used to analyze the model accuracy, the key parameters of the model was simulated and the influence of key parameters including interframe delay and gesture angles on the RS distortion were discussed. The experimental results indicate that when the measuring errors of height, speed and the gesture angles are less than 0.09 km, 0.3 km, and 0.02°, respectively, the calculation error of this model is less than 1/3 pixel. These results demonstrate the effectiveness of the model. It concludes that this model can be the theoretical foundation of quantitatively analyzing RS effect of large frame CMOS aerial cameras and can offer some theoretic guidances for applying CMOS in the field of aerial cameras.