Abstract: In order to meet the demands of the calibration for ground equipment, a new type of highprecision star magnitude simulator with limited space and full spectrum was presented. The optical system structure of the star magnitude simulator was designed to be the compact structure space. The control system based on the pulse width modulation (PWM) technology can realize the digital adjustment of the LED light intensity from 640 lx to 1.0 lx. The system which was drived by PT4115 used the white light XLamp LED as the light source. Compared with the traditional analog adjustment star magnitude simulator, the new star magnitude simulator has the characteristics of small volume, low heat and high stability, etc. Through the application in dark room environment, the analysis and test results show that the 0m~7m magnitude stars can be simulated, the spectral range can cover the whole visible light, and the control precision of the star magnitude is up to 0.1m.