The use of fisheye image stitching is a popular method to produce panoramic images rapidly. A fisheye lens with a large angle can reduce the number of times of image acquisition, but distortion makes the registration of images difficult. As a key determinant of the effect of fisheye image mosaic quality, the estimation of external parameters of images has become a core issue in panorama generation. Previously established methods require additional measurement devices or are only suitable for specific scenarios. In this study, we develop an image mosaic method. A large-angle fisheye lens is adopted for conformal projection and spherical matching. First, to facilitate the search for corresponding corners, the source images are rotated by 90°. Then, conformal projection transformation is utilized to present the feature structures of the overlap area of two images in a consistent manner. Second, the searched corner points are projected onto the unit sphere, and the motion parameters are estimated with the direct linear transform method. Experimental results show that our method can efficiently complete image registration with a large angle between fisheye images. Hence, a full-view panoramic image of 360°×180° can be obtained with the use of two fisheye cameras with an angle of more than 180°.