[Objective] The spatio-temporal differentiation and driving factors of farmland ecosystem carbon source-sink effects in Guangdong Province were analyzed in order to provide a valuable reference for the scientific and rational formulation of regional agricultural carbon reduction and carbon sequestration measures in the region.[Methods] Quantitative assessment of the spatial-temporal distribution of carbon source-sink effects in farmland ecosystems in Guangdong Province from 2010 to 2020 was conducted by using the parameter estimation method and GIS spatial analysis. The driving factors of spatial differentiation of the carbon source-sink effect in farmland ecosystems were determined by using the LMDI factor decomposition model.[Results] ① The level of carbon source-sink effects in Guangdong Province farmland ecosystems continued to maintain a good, positive development trend, and the effects of reducing emissions and sequestering carbon gradually became prominent. Specifically, the total carbon sequestration fluctuated and increased, and rice, sugarcane, and vegetables were the main carbon sources. Carbon emissions were effectively controlled, and the effect of reducing emissions was becoming increasingly evident. Rice planting and agricultural inputs were the main carbon sources. Moreover, the growth of carbon sequestration in farmland ecosystems effectively offset the growth of carbon emissions. ② The spatial heterogeneity of carbon source-sink effects of farmland ecosystems was obvious, and the overall distribution was relatively clustered. Zhanjiang was the main high-carbon source-high-carbon sink area, while low-carbon source-low-carbon sink areas were mainly found in the Pearl River Delta region. ③ Economic factors were the key driving force causing increased carbon sequestration in farmland ecosystems, while structural factors exhibited inconsistent responses and varied with their locations. Efficiency factors and labor force factors, on the other hand, had a restraining effect.[Conclusion] The carbon source-sink effect of farmland ecosystems in Guangdong Province exhibited a continuous increasing trend overall, but there were significant regional differences. Therefore, measures to reduce emissions and sequester carbon in agriculture should be tailored to local conditions, taking into account the differences in the driving effects of economic, structural, efficiency, and labor force factors in each region.