Abstract: Star sensor is a kind of attitude measurement system, which is used to measure the real-time posture of the aircraft. A new kind of optical system of star sensor based on CCD was designed. And the calculation of relevant parameters was carried out. This kind of optical system with wide field of view, wide spectra range and good imaging quality was realized in ZEMAX software. This optical system has an effective focal length of 50 mm, an F-number of 1.8, a field of view of 23 degrees, a spectral range of 500-850 nm and a primary wavelength of 680 nm. The capture probability of three navigation stars is up to 100%. The especial requirements of the spot, encircled energy, distortion etc. are all satisfied. Lateral color is corrected greatly. The value is 0.087 m .The system only contains 6 pieces of lens. The structure is not only simple and compact, but also easy to manufacture.