Abstract: In order to explore the dynamics of CO₂ flux exchange and its regulating mechanism of mangrove in Guangxi, the CO₂ flux data and the meteorological data of sandy mangrove recorded by the eddy covariance system at the mangrove ecological observation and experiment station in Beihai in 2019 were utilized to analyze the dynamics of net ecosystem carbon exchange (NEE) and its response to meteorological factors. The results suggest that the diurnal variation of NEE on average followed a U-shape pattern in Guangxi. The carbon sink reached the maximum in February and the minimum in June on the monthly scale. On the seasonal scale, the maximum NEE occurred in autumn, followed by spring, winter, and summer. The cumulative monthly NEE reached the maximum of -45.23 g·m^-2·mon^-1 in November and the minimum of -16.95 g·m^-2·mon^-1 in July. The total amount of NEE, ecosystem respiration, and gross primary productivity (GPP) were -386.68, 862.49, and -1 249.18 g·m^-2·a^-1, respectively, which were lower than that in the mixed mangrove in Fujian and Guangdong. The dominant factor of direct influence on the net ecosystem exchange was the photosynthetically active radiation, and that of indirect influence was vapor pressure deficit. Precipitation was the limiting factor of net ecosystem exchange.