Current space target simulation systems suffer from limitations, such as a single simulated spectral band, inability to allocate spectral ratios between bands, and poor imaging quality of multi-spectral simulated images. We propose a multi-source information fusion spatial target simulation method system that features a “series-parallel” hybrid connection. We optimize the design of a multi-spectral common aperture optical system and experimentally verify the proposed method. The experimental results show that the proposed system can simulate a wide range of spectral bands ranging from ultraviolet to long-wave infrared. Furthermore, it achieves precise control over the ratio of simulated radiant energy among spectral bands, with a spectral simulation error of less than 4.8%. Notably, it effectively images stars against the cosmic background and spacecraft across different spectral bands. This system serves as a theoretical cornerstone and provides crucial technological support for performance testing and rapid iterative development of multi-source information fusion space exploration systems.