Carbon-oxygen balance estimation can quantify the equilibrium state between natural ecosystems and human activities from the source. It holds significant practical importance for achieving the "Dual Carbon" goals (peaking carbon emissions and achieving carbon neutrality) and fostering high-quality development. Based on methodologies including the carbon-oxygen balance method, gravity center model, and Exploratory Spatial Data Analysis (ESDA), this study analyzed the spatiotemporal evolution of China's carbon-oxygen balance from 1990 to 2020 and projected the ecological land demand required to achieve the carbon-oxygen balance target for the year 2030. The spatio-temporal evolution of carbon sequestration/oxygen release volumes and the carbon-oxygen balance at the provincial scale across China reveals the following key findings: (1) Temporally, the national total carbon sequestration and oxygen release volume experienced a slight overall decrease of approximately 2.32% over the period of the past thirty years. Spatially, there were significant regional disparities, the western regions consistently exhibited higher carbon sequestration and oxygen release capacities compared to the eastern regions. Among all areas, Shanghai within the Yangtze River Delta region demonstrated the most significant decline, with its carbon sequestration/oxygen release volume plummeting by up to 34%. (2) Regarding regional carbon-oxygen balance, eastern regions (particularly the Beijing-Tianjin-Hebei area and the Yangtze River Delta) suffered from severe imbalance. Their carbon-oxygen balance coefficients were substantially higher than those in the west, indicating a more critical oxygen deficit. Shanghai exhibited the most dramatic increase, with its carbon and oxygen balance coefficients rising by 210.20% and 247.84%, respectively, over the 30-year period. (3) The migration trajectory of the gravity center for the carbon-oxygen balance coefficient demonstrated spatiotemporal consistency, persistently shifting towards the southwest. Spatially, the pattern was characterized by High-High agglomeration in the eastern and central regions, and Low-Low agglomeration in the western and southwestern regions, as identified through ESDA. (4) To achieve the 2030 carbon-oxygen balance target, regions like Beijing-Tianjin-Hebei and the Yangtze River Delta would require substantial increases in differentiated ecological land, with oxygen balance posing a greater demand. For areas like Shanghai, achieving balance solely through land expansion proved highly challenging (requiring land increases exceeding 500%-1200%), urgently necessitating economic transition and emission reduction. In the future, This study can provide relevant scientific references for achieving China's carbon-oxygen balance goals. In conclusion, China faced severe carbon-oxygen imbalance during the study period. The impact of the southwestern region on China's carbon-oxygen balance status is gradually increasing. In the future, ecological land use planning and allocation strategies under different objectives needs to be considered. This study can provide relevant scientific reference for the realization of carbon-oxygen balance objectives in China.