Abstract: The north of the South China Sea has the most unstable Valley Group sedimentary environment in the shelf slope system. It is not only a marine organic carbon deposition area, but also a channel for material transfer between the shelf and the deep sea. In this study, the upper sediment samples (0～30 cm) of Yitong gorge and Dongsha Islands sea slope were collected in 2019 and 2020 respectively to study the vertical distribution characteristics of organic carbon content and infrared absorption intensity, and to explore the migration and deposition of organic carbon in the slope environment. The results show that the organic carbon content in the upper sediments of Yitong gorge gradually decreases from the upper slope, middle slope to the lower slope, which are 1.14%～2.02%, 1.01%～1.46% and 0.60%～2.15% respectively. The organic carbon content in the upper sediments of Dongsha Islands sea area is 0.52%～1.35%; the vertical variation of organic carbon in the four stations was not similar. The infrared absorption spectra of organic matter in the upper sediments of the study area showed three peak areas: 500～1500 /cm, 2300～2500 /cm and 3400～4000 /cm; the results show that the infrared absorption characteristics of organic matter on the slope of Yitong gorge are similar to those under the slope, and the absorption intensity decreases with the depth, while the infrared absorption intensity of organic matter in the slope does not change significantly with the depth; the infrared absorptivity of organic functional groups in Dongsha Islands sea area increased abruptly in the middle layer. During the migration process of organic matter in the canyon sediments in the study area, the organic matter directly migrated from the adjacent Canyon slope to the slope through landslide debris flow, which was difficult to remain in the slope. The vertical distribution of organic matter in the slope is more uniform.