A hollow ellipsoidal earth simulator optical system emitting ultraviolet (UV) is designed, half of the sphere is illuminated by the UV light source, the other half is not illuminated. It′ s combined into a number of LED components and light array working to achieve the luminescence brightness of 0.2~1.2 W/(sr·m2) adjustable within the spectral range by controlling the UV LED lamps, and the inhomogeneity of surface emitting brightness is better than 20% ; so the geometric and radiation characteristics of the earth under different brightness conditions can be simulated. The composition and working principle of the earth simulator is introduced, the inhomogeneity of the earth simulator′s radiation brightness is analyzed using the optical analysis software called Lighttools, and the deformation of the opto- mechanical structure of the high orbit UV earth simulator at 0 ℃~45 ℃ is analyzed by the finite element analysis software called Ansys. The results show that the inhomogeneity of sphere surface brightness is 9.5%, the maximum average of the radiance is 1.42 W/(sr·m2), the deformation of the optical mechanism influenced by temperature is very tiny and the design requirements are fully satisfied.