ing at the deficiency of the design of irradiance attenuators for solar simulators, we proposed a new design method of attenuators to improve their irradiance uniformity. According to the theory of Etendue, the mesh area of an attenuator was calculated and the radiation flux in the convergent optical path was modulated. Furthermore, the radiation distribution on the attenuator was theoretically analyzed by the zoned method of condenser. Then, the structure of non-uniform mesh distribution was designed to modulate the radiation distribution in the convergent optical path and the specific design parameters were provided. In addition, the effects of attenuators with uniform and non-uniform mesh distributions on radiation modulation and irradiance uniformity were compared and analyzed. The results suggest that the irradiance of 0.1--1.0 solar constant can be output continuously after an attenuator with non-uniform mesh distribution was installed and the power of xenon lamp was adjusted. Besides, after the modulation of radiation distribution, the maximum reduction rate of irradiance non-uniformity in the spots is 48.7%, and the wide adjustment of irradiance at low irradiance non-uniformity can be realized, which has certain reference significance for improving the performance of solar simulators.