Abstract: The working principle of star sensor based on the charged coupled device (CCD) technology was explained, as well as its important role playing in space positioning. The star sensor was needed to be calibrated by the star simulator using the ground calibration technique. According to the two basic parameters of the stellar light source, the simulation methods of the color temperature and the magnitude were proposed respectively. The realization of the star simulator was studied, and the electric light source, waveband light intensity controller, magnitude controller were designed. The entire system was assembled in laboratory, and the controlling and testing platform was set up. The experiments were carried out and the obtained results show that this system has high reliability. In the peak spectral range of 350 nm~950 nm, it can simulate the magnitude in 0~+6.5MI and the equivalent blackbody temperatures of the star: 2 600 K, 3 600 K, 4 300 K, 5 000 K, 5 500 K, 6 000 K, 6 800 K, 7 600 K, 9 800 K, the relative intensity error is better than 0.10.