A LED-based single star simulator system with multi-color-temperature and multi-star-magnitude output is developed to calibrate star sensor′s optical signal, and it can significantly diminish the calibration error caused by the non- matching between star simulator′ s color temperature and star sensor′ s detecting color temperature. The mechanism of how color temperature′ s non- matching affects star sensor′ s optical signal calibration accuracy is analyzed. The design scheme of LED-based single star simulator is determined, which is divided into four key issues, the determination of light source, the design of drive circuit and control system, the design of color temperature and star magnitude matching algorithm, and the design of control software. The LEDbased single star simulator is calibrated and tested, the spectral matching errors of starlight with 4000 K color temperature, 0 star magnitude and starlight with 7000 K color temperature, 3 star magnitude are 6.37% and 8.76% respectively, and their star magnitudes are 0.03 and 2.93 respectively. The irradiance non-uniformity in Φ100 mm area of LED-based single star simulator is 6.5%. They all meet design requirements.