Abstract: Mercury retrograde is an astronomical phenomenon caused by the relative motion of mercury and earth. Accurately describing and predicting the “mercury retrograde” phenomenon is of great significance for the calibration of astronomical observation instruments, the selection of launch and operation task time windows, etc. In this paper, based on high-precision ephemeris data (DE440), the position of mercury is obtained, and the trajectory of mercury in the equatorial inertial coordinate system relative to earth is simulated and modeled from 2024 to 2044. The retrograde time of mercury is calculated based on the rate of change of right ascension, and the spatial and temporal distribution characteristics of the retrograde trajectory are explored. The results show that the number of times that the “mercury retrograde” phenomenon occurs in different years is different, with 3～4 occurrences per year.The average duration of “mercury retrograde” is about 23 days (with a fluctuation range of 20～26 days), and the average interval between two consecutive retrograde periods is about 95 days (with a fluctuation range of 89～103 days).There is a similarity in the retrograde trajectories of mercury in different years, especially in the years that are 13 years apart (such as 2024 and 2037).In addition, there will be a retrograde of mercury that spans two calendar years on average every 4～5 years.

Key words: retrograde motion of water, DE440, rate of change of right ascension, spatial and temporal distribution characteristics