A novel high magnification zoom laser beam expander is proposed originally. The zoom part and fixed part of the beam expander both adopt spherical lens and the compensation part comprising a spherical surface and an aspherical surface. The structure parameters were given by using geometry optics.The zoom characteristic and image quality were also analyzed.The results show that the magnification of the beam expander can be adjusted continuously from 3 to 20. Compared with other congener spherical zoom system,the beam expander has the advantages of high magnification,compact structure,high beam quality and high transmission efficiency.The novel expander can be used in many fields effectively. A novel high magnification zoom laser beam expander is proposed originally. The zoom part and fixed part of the beam expander both incorporated spherical optics and the compensation part comprising a spherical surface and an aspherical surface. zoom characteristic and image quality were also analyzed. results show that the magnification of the beam expander can be adjusted continuously from 3 to 20. Compared with other congener spherical zoom system, the beam expander has the advantages of high magnification, compact structure, high beam quality and high transmission efficiency. The novel expander can be used in many fields effectively.