Concerned with the nonlinear distortion problems varying with the focal length of aerial optical zoom lenses, a rapid geometric correction method based on combining the offline calibration on the ground with the online correction on board is presented. The one- parameter division model is adopted to correct the radial nonlinear distortion of lens. According to the perspective projection invariance of collinear points in template images, an optimization searching method of variant step length is adopted to estimate the optimal distortion coefficients and the distortion center coordinates of zoom lenses on the conditions of a few discrete focal lengths. The variation laws of the distortion parameters with the focal lengths are discussed by experiments finding, and the corresponding empirical formulas are established. In the actual flight test, the distortion parameters corresponding to the actual measured focal length value are calculated based on the empirical formulas to correct the lens distortion in the real scene images. Correction results of the template images and the real scene images show that this method can effectively correct the nonlinear distortion of zoom lenses. The average root mean square error of three 720 pixel×576 pixel images of template at different focal lengths is about 2.68 pixel, and the average correction time is 4.82 s. This correction method has the advantage of high efficiency, and easy to realize automatic correction for engineering applications.