In this study, a model of remineralization patterns was developed to explore the particulate organic matters (POM) decomposition process among marine mesopelagic zone (200 to 1000 m) using data from the South China Sea. The results suggest that three high C/N remineralization patterns are identified at 200 to 400 m, 600 to 700 m and 900 to 1000 m, and two low C/N remineralization patterns are found at 400 to 600 m and 700 to 900 m. These findings indicate three increasing trends and two decreasing trends of C/N ratios in POM, which are further confirmed by measured C/N data in POM from the global ocean. Only the exposed POM has the chance to experience the selective remineralization process, thus the C/N ratios in POM of the remained particles are closely related to selective preservation of specific bio-macromolecules, aggregates, zooplankton community structure at different depths and the microbial loop.