China's carbon emissions, the highest globally, were studied to understand factors influencing carbon intensity. Using factor decomposition models, researchers analyzed carbon emissions and economic decoupling, laying the groundwork for sustainable economic development. They measured and analyzed carbon emission intensity across 29 Chinese provinces and cities from 1998 to 2019. Findings show: 1) Carbon intensity varied over time and industries, with gradual overall decline and regional differences lessening. 2) Technological progress had the largest impact on carbon intensity reduction in the secondary industry. 3) Industrial structure influenced primary and tertiary industries. 4) Decoupling improved over time, with technological progress leading the way. Recommendations include enhancing technology, upgrading industries in less developed areas, and supporting regional development and clean technologies.