Based on the IPCC emission factor accounting theory and employing the life cycle assessment(LCA) method, a carbon emission accounting framework for sponge cities was constructed by considering the carbon emission sources at different scales and locations in sponge city construction. Taking the national sponge city pilot area in Shenzhen as a case study, the full life cycle carbon emissions of typical sponge facilities and sponge city construction projects were calculated, and the key factors affecting carbon emission levels were analyzed. The results indicate that sponge facilities such as green roofs and rain gardens exhibit negative net carbon emissions over their life cycle, with carbon reduction benefits exceeding 40 kg/m2. However, permeable pavements and roads have positive net carbon emissions, as their carbon emissions outweigh carbon sequestration. Indirect carbon emissions dominate the carbon footprint of sponge facilities, with the planning and construction phases contributing to majority of emissions. Carbon sequestration primarily comes from green space carbon absorption, followed by rainwater utilization and building energy savings. Residential sponge projects achieve carbon neutrality after approximately 12.4 year of operation, generating a total carbon reduction benefit of about 183.61 t/ hm2, over a 30year life cycle. Road and square projects may also achieve carbon neutrality under optimized sponge facility layouts. This study demonstrates that sponge cities can play a significant role in carbon reduction, effectively promoting lowcarbon urban development. Future sponge city construction should prioritize the use of lowcarbon materials, optimize facility layouts, and enhance carbon sequestration through diversified emission reduction strategies.