Litter is an important part of terrestrial ecosystem. It affects the formation of soil organic matter, the supply of plant nutrients and the absorption and storage of soil carbon. In order to explore the mechanism of carbon water coupling at litter soil interface and the interaction between the two, this study focuses on the changes of litter characteristics during litter decomposition and its impact on soil carbon pool and soil carbon water relationship. Litter decomposition is mainly reflected in the reduction of litter volume and carbon content. In the study of litter, scholars pay more attention to the rate of litter decomposition and the release of nutrient elements and other trace elements and organic constituents during litter decomposition. And the litter decomposition is significantly affected by temperature and moisture. Litter decomposition also has significant effects on soil organic carbon, soil respiration and chemical nutrients. The soil water holding capacity is enhanced during litter decomposition. The changes of soil water content contribute to the changes of soil structure and physical and chemical properties, and then affect the stability of soil organic carbon and soil microbial activity. This study is of great significance for accurately predicting the dynamic changes of carbon and water at the litter soil interface and the carbon cycle of terrestrial ecosystem in the future, which also provides a reference for the further study of the related mechanism of forest litter soil interface.