Abstract: To achieve solar irradiation with large spot diameter, the divergent solar simulator with large irradiated surface was designed. The short arc xenon lamp was selected as light source based on the characteristics of solar spectrum distribution. The mathematical model for light source was built. Considering imaging ratio and peak brightness xenon arc point relative to defocus, the optical filter and condenser system was designed, the irradiate uniformity of the solar simulator was improved. At the same time, based on the spectral characteristics of short arc xenon lamp, a spectral matching model was established, the optical filter transmittance at different wavelengths was designed. Experimental results show that the divergent solar simulator has large irradiation area about 2 m, When the working distance is 6, 8, 10 m, the irradiation non-uniformity of the simulator is superior to 3.33%, 3.51% and 4.3% respectively, and the spectra match A level standard of the AM1.5 solar spectrum.