With the development of aerospace field, there exists an increase in the need of space environment simulation and solar radiation simulation has also attracted much attention. At present, most of the mature solar simulators designed and used are horizontal solar simulators, whose collimator mirrors usually adopt the form of splicing. However, the vertical solar simulators possess the advantage of space-saving and become gradually mature. In this paper, according to the general requirements of solar simulators, a large diameter overlooking multi-dimensional adjustable structure of collimating mirrors used for a high irradiation vertical solar simulator is designed. In addition, according to the characteristics of high radiation and low background working environment, a multi-dimensional adjustable flexible hoisting structure is designed. In order to improve the overall debugging performance of the system, a single-block whole mirror structure is adopted to reduce the structural complexity. According to the above designs, the calculation and simulation analysis are conducted and the results show that the flexible hoisting structure can be used to effectively balance the stress deformation caused by the collimating mirror's own gravity and the environmental temperature, and finally to meet the use requirements of irradiance and irradiation uniformity for the solar simulators.