Abstract: Under central catadioptric camera, the image of a line is a conic curve. Due to the partial occlusion, it is very difficult to correctly estimate the catadioptric line image from its visible part, and the existing methods in the literatures cannot still solve this problem effectively. Except for the necessary and sufficient conditions that must be satisfied by a set of paracatadioptric line images, we find that if the antipodal points of image points on the visible arc are known, the fitting accuracy can be improved greatly. Thus, in this paper, based on this idea, a new method for fitting paracatadioptric line images is proposed. Firstly, a new relationship between a pair of antipodal image points and the camera principal point are derived. Next, using this relationship, a new method is proposed to estimate the paracatadioptric line images. Finally, the camera intrinsic parameters are calibrated using the estimated conics. Experimental results on both simulated and real image data have demonstrated theeffectiveness of the method.