In this study, we proposed a method to design an optical system for conducting a specific type of aircraft cabin thermal load tests. Thus, a solar radiation simulator was developed. Herein, a single lamp was designed; subsequently, the spatial structure of the lamp was studied. A reasonable installation location for the lamp was ascertained using the pre-adjustment method. Further, the optical system was processed and installed according to the design scheme. Some relative tests were also performed. The results prove that the calculation error associated with the irradiance distribution is 12.0%, demonstrating the feasibility of the proposed method. Furthermore, the deviation between the thermal effects obtained based on the calculation and design value is -3.1%, proving that the system achieves the expected requirements. The temporal instability associated with the irradiance is ±0.52%, and the system exhibits favorable stability. This study is expected to have a considerable reference value with respect to the design of a solar radiation simulator.