The moon has the advantages of high stability, gentle variation of reflectance spectra, low background influence, and being free from atmospheric effects when used for satellite in-orbit radiation calibration. As lunar radiation is affected by factors such as lunar phase angle, lunar alignment, and distance between the sun and the moon, lunar calibration necessitates long-term ground-based observation to establish a high-precision lunar radiation model. Therefore, an automatic tracking system for the ground-based lunar spectral irradiance meter was designed in this paper. The preliminary tracking for the system is achieved by calculating the zenith and azimuth angles of the moon using the lunar position algorithm, and then precise tracking is accomplished through image processing of the lunar images captured by a CCD camera. The outdoor tracking observation experiments show that, the tracking approach combining lunar position calculation and image processing tracking possesses relatively high precision, with an average tracking accuracy within 0.04°, validating the high accuracy and reliability of the lunar tracking system.