Abstract: The bottom-up terrestrial biosphere models, Boreal Ecosystem Productivity Simulator (BEPS), and VEgetation-Global-Atmosphere-Soil version (VEGAS), along with top-down optimization results from multiple atmospheric inversions in the OCO-2 v10 MIP were used to assess the size and spatial distribution of China’s carbon sinks during 2015−2019. Additionally, combined with the boundaries of the four major geographic divisions in China and land-use data, the carbon sink intensities of the four major ecosystems—forests, grasslands, shrublands, and croplands—were further clarified. Overall, China’s terrestrial carbon sink exhibited a spatial distribution characterized by higher uptake in the southeast and lower uptake in the northwest during 2015−2019. The annual average carbon sinks estimated by BEPS, VEGAS, and OCO-2 v10 MIP models were 0.38±0.04 Pg(C) a⁻¹, 0.22±0.03 Pg(C) a⁻¹, and 0.54±0.05 Pg(C) a⁻¹, respectively, demonstrating convergence between the top-down and bottom-up estimates. During the summer months (Jun–Aug), China’s terrestrial ecosystems exhibited the highest capability for CO₂ uptake. In terms of regional carbon uptake, BEPS and the ensemble average result from OCO-2 v10 MIP consistently indicated that the southern region of China had the largest carbon sink size. Conversely, VEGAS revealed that the northern region of China exhibited a larger carbon sink. Additionally, BEPS and the ensemble average result from OCO-2 v10 MIP indicated that the forest ecosystems had the largest carbon sinks, with intensities of 0.21±0.02 Pg(C) a⁻¹ (47.2%) and 0.26±0.02 Pg(C) a⁻¹ (46.0%), respectively. However, VEGAS showed a lower carbon sink of 0.06±0.04 Pg(C) a⁻¹ for the forest ecosystems (23.9%), slightly lower than that of the crop ecosystems. In summary, the forest ecosystems emerged as significant carbon sinks in China. Nevertheless, achieving consistency in the distribution and intensity of carbon sinks using various methods remains a substantial challenge.