A star simulator using digital adjustable light sources and a collimating optical system is presented to realize a laboratory test of celestial navigation equipment in this paper,and the technical requirements of the background light simulation are proposed as well.Based on the technical requirements of celestial navigation equipment, the overall construction of the star simulator is presented.Then, the key techniques of digital adjustable light sources, achromatic collimating optical system and adjusting for the sizes and positions of the stars are introduced, and the effect of the uniformity of background light on the star simulation is analyzed.Finally, the star simulator is fabricated and the corresponding experiments are carried out for validating its properties.Experimental results indicate that the simulator can simulate the star magnitudes of 0-5 effectively,and can offer the uniformity of background light of 94.7% and collimation better than ±2″ in the system focus of 1 647 mm and the field of view of 28′.Furthermore,the designed simulator can simulate the changes of star lights and background lights at the same time.It is concluded that the designed star simulator can satisfy the test requirements of celestial navigation in a laboratory.