Abstract: In face of global climate change challenges, assessing carbon effects of land reclamation engineering is critical for achieving "dual carbon" goals．A carbon accounting methodology for land reclamation engineering has been developed, covering three aspects: project implementation, land use structure adjustment, and land use efficiency improvement．Taking a typical land reclamation engineering in Jiangsu Province as a case study, empirical analysis showed that total carbon emissions during construction phase reached 7949600 kg CO₂, with concrete and steel consumption identified as main carbon sources（accounting for 65.41%）．Land use structural adjustment achieved a net carbon sink increase of 309383.00 kg CO₂ through cultivated land expansion．However, field management improved crop carbon absorption capacity（rice/wheat carbon absorption increased by 4.06%）, while carbon emissions of fertilizer application and irrigation rose by 4.06%．These findings play a positive role in promoting land reclamation high-quality development and supporting national "dual carbon" goals．