The carbon sequestration capacity of vegetation is the foundation of terrestrial ecosystem carbon sink, which can be reflected by Net Ecosystem Productivity (NEP). How to quantify the vegetation carbon sequestration capacity of terrestrial ecosystems is a common scientific issue in the research fields of terrestrial surface ecosystems and ecology. Estimating the carbon sequestration capacity of vegetation, as well as identifying its dynamic characteristics and influential factors, holds immense importance for the sustainable development of regional ecosystems. Focused on the Beijing-Tianjin Sandstorm Source Control Area, this study estimated the NEP from 2000 to 2020, analyzed the spatio-temporal variation characteristics of the area using methods such as trend analysis and stability analysis, and explored the natural and human activity factors that affected the NEP by the Geodetector. The main results showed that: (1) In 2020, the average NEP of the Beijing-Tianjin Sandstorm Source Control Area was 110.09 gC m^-2 a^-1, and the carbon sink area was about 3.591×10⁵ km², accounting for 78.80% of the total area. (2) From 2000 to 2020, the average annual NEP in the Beijing-Tianjin Sandstorm Source Control Area was 77.54 gC m^-2a^-1, with an interannual variation rate of 4.118 gC m^-2a^-1, showing an overall upward trend. The study area was mainly characterized by a significant increase in NEP, accounting for 55.16%, and the significantly increased area was mainly distributed in the southern part of the study area. Conversely, regions with a declining NEP constituted a mere 0.15% of the total area, primarily located in the northern arid grassland desertification control area and appearing sporadically. (3) The NEP of different ecosystems in descending order was forest land, farmland, and grassland. The forest land had a strong carbon sequestration effect, and its NEP showed an upward trend, indicating a greater potential for carbon sequestration in the future. The grassland accounted for 70% of the research area, and its total carbon sequestration was much higher than other types, showing an increasing trend. (4) The primary influencing factor of NEP in the study area was annual precipitation, while the ecological engineering was also an important influencing factor of NEP. The NEP in the study area was influenced by multiple factors, manifested as dual factor enhancement or non-linear enhancement. Based on the estimation of vegetation carbon sequestration capacity and spatial differentiation of influencing factors, this study also proposed suggestions for spatial restoration to some extent, to provide scientific basis for decision-making on strengthening vegetation carbon sequestration capacity and ecological restoration for the Beijing-Tianjin Sandstorm Source Control Area.