The robust carbon source/sink function of forest ecosystems is identified as the most economical and effective natural climate solution for achieving the strategic objectives of carbon neutrality and carbon peaking. Accurately assessing the carbon sequestration capability of forest ecosystems is crucial for determining forest carbon storage. In order to clarify the carbon flux characteristics and their driving factors in the evergreen-deciduous broadleaf mixed forest in the North-South climate transition zone, observations of carbon flux and environmental factors were conducted in the Dabie Mountains' evergreen-deciduous broadleaf mixed forest using eddy covariance method from 2011 to 2020. The results revealed that the net ecosystem exchange (NEE), ecosystem respiration (Reco), and gross primary productivity (GPP) of this forest were -788.13 gC m^-2 a^-1, 1074.14 gC m^-2 a^-1, and 1862.27 gC m^-2 a^-1, respectively. This forest ecosystem was overall a carbon sink, with its carbon sequestration capacity being comparable to similar latitude evergreen-deciduous broadleaf mixed forests and higher than other types of forest ecosystems like the mixed coniferous-broadleaf forests and bamboo forests. Over a decade, the carbon sequestration capacity of the Dabie Mountains' evergreen-deciduous broadleaf mixed forest has increased. The carbon flux in this forest was significantly influenced by temperature and solar radiation. Air temperature (Ta), net radiation (Rn), Photosynthetically Active Radiation (PAR), and total radiation (Rg) showed significantly positive correlation with the ecosystem's Net Ecosystem Productivity (NEP) and GPP (P<0.001); Reco showed significantly positive correlation with Ta and Rn (P<0.001). The findings provide observational data support and scientific basis for the estimation of carbon storage and simulation of carbon cycling processes in forest ecosystems of the north-south climatic transitional zone, which are sensitive to climate change.