Lobster-eye optics is a promising option to establish an all-sky monitor in the X-ray spectrum. With the development of micromachining technology, the performance of lobster-eye optics is gradually improving and has become more practical. In this paper, from an optical design point of view, the mathematical models of the square-channel lobster-eye lens and the meridional lobster-eye lens have been established based on prism analysis, and the focusing property differences of the two lenses are analyzed. There are several key conclusions: the square-channel lobster lens has no paraxial ideal focal point; the meridional lobster eye lens has better energy concentration for focusing and a weaker capacity for energy collection than the square-channel lobster eye lens in the high-energy X-ray spectrum; and the stray light arms of the square lobster-eye lens appear earlier than those of the meridional lobster-eye lens when the photon energy decreases. These conclusions can help improve the design of a lobster-eye lens for space detection and exploration.