The invention relates to a sun-tracking correction system and method based on a celestial body image, and the system comprises an image collection module which is used for collecting an image of a celestial body in a view field, and transmitting the data to a data analysis module. The data analysis analyzes the deviation between the celestial body image and the center of the image in an image coordinate system, and transmits the deviation value to a correction calculation module. The correction calculation module decomposes the deviation value to corresponding rotation axes in a mode that a sun-tracking mirror rotates, and obtains the error angle of each rotation axis. The system also comprises the data storage module which is used for storing a correction result of the sun-tracking mirrorand a single-correction-period control command list of the sun-tracking mirror. A communication module reads the single-correction-period control command list from the data storage module, and transmits the single-correction-period control command list to the sun-tracking mirror, and controls the image collection module to carry out photographing according to the rotating period of the sun-tracking mirror. The system moves according to a law, takes the celestial body with certain brightness as a mark object. The system can carry out the correction during day and night, and improves the correction efficiency while reducing the impact on the power generation efficiency.