Cultivated land carbon sequestration as an effective supplement to the terrestrial ecosystem is recognized; however, research on the carbon sequestration function of cultivated land has been conducted from the perspective of ecology. For example, carbon uptake and carbon release of vegetation and arable soil and carbon balance in agro- ecosystems is often a focus and there is a lack of research into the carbon sequestration of cultivated land from the viewpoint of land science. Here we built a basic research framework for the carbon sequestration function of cultivated land use for the Huang-Huai-Hai Plain based on the carbon cycle process of cultivated land use system theory. Then the carbon sequestration function was evaluated from three aspects of carbon sequestration ability, carbon sequestration efficiency and carbon sequestration dominance. The results suggest that the carbon sequestration function of cultivated land use can be known from four aspects: natural carbon sequestration ability, ideal carbon sequestration ability, practical carbon sequestration ability and regional carbon sequestration ability. The carbon sequestration of cultivated land use systems of the Huang-Huai-Hai Plain is a carbon sink. The carbon sequestration efficiency and carbon sequestration dominance degree are 2.5 and 0.85 respectively. The carbon sequestration function of cultivated land use system plays an irreplaceable role on the Huang-Huai-Hai Plain, which should be a prominent function in this area. This study provides a new way of thinking about ecological function theory research for cultivated land, and support for promoting the ecological benefits of cultivated land, mitigating climate warming, and administering cultivated land ecology interregional compensation.