A light source of multi-star simulator capable of background adjustment and magnitude control has been designed. Two integrating spheres are employed as the star-point light source and the background light source respectively. A beam splitter prism has been designed to serve as the beam combiner for the star-point and the background light sources, and a mathematical model has been constructed respectively to compute the light flux of the two integrating spheres. A magnitude testing system and a background testing system have been created using low-light illuminometer, luminance meter, and testing instruments to measure the star-point magnitude and the background luminance of the multi-star simulator. The test results suggest that the star-point magnitude is adjustable from 0 to +5mv
, with a simulation precision superior to ±0.026mv
. The maximum background luminance is 3.8×105
, and the minimum background luminance is 6.4×10-2
. The designed light source system can meet the requirements for simulating the stellar map with a sky background.