Omnidirectional camera is useful for surveillance because the camera captures surrounding images at a time. However, when this kind of camera is installed at the corners, such as room entrance or walls, part of its surrounding may be occluded and the advantage of the camera cannot be fully utilized. To solve the problem, in this paper, we have proposed a new type of mirror for omnidirectional cameras, which is an asymmetric hyperboloid mirror. The mirror is divided into multiple parts. Some parts of them are tall and thin, and others are short and wide, to make it be adaptable to various kinds of environments. The tall and thin hyperboloid is lower in imaging quality but better in the range of view, while the short and wide hyperboloid has higher imaging quality but with less range of view. In this paper, the model of hyperboloid mirror and its projection formula are presented. The experimental results show how the adjustments of hyperboloid parameters affect the imaging quality and the range of view. Besides the imaging quality is less being influenced than the range of view.