Given the parameters of the mirror shape and the camera, a self-calibration method for catadioptric camera system is proposed to estimate the mirror pose with respect to the camera by using only one image containing no special designed calibration pattern. The ellipse corresponding to the mirror boundary in the image is used to compute possible mirror pose by planar circular posture estimation. With two pose candidates thereafter, the correct pose and the parameter of lens boundary simultaneously is found by matching the predicted and the observed image of lens boundary. The method features easy-operating, high accuracy and is suitable for non-single viewpoint system. Experimental results both on synthesized and real images demonstrate the validity of our method.