Abstract: This paper is the result of 1:1,000,000 marine geological survey engineering. Objective Quaternary sedimentary thickness can not only reflect the provenance and sedimentary characteristics, but also reflect the tectonic activity characteristics to a certain extent. Methods Based on a large number of single channel and multi-channel seismic data and verified by drilling holes, the Quaternary thickness map of the SCS was compiled. Results The thickness of quaternary sediments in the South China Sea (SCS) varies a lot, with the maximum thickness over 2000m and the minimum one close to 0. ConclusionsSedimentary and subsidence centers were formed in the western margin of SCS, including Yinggehai, Zhongjiannan and Wan'an sea area, which indicates that the fault zone in the western margin is still active in Quaternary period and controls the development of these subsidence centers. The development of NE trending sedimentary centers on the northwest continental slope of the South China Sea may indicate that the northwestern SCS is still dominated by extension in quaternary. The thickness of quaternary in Dongsha sea area is near 0, indicating that the area has been continuously uplifted and washed by strong current since quaternary. Therefore, the northern South China Sea shows a pattern of subsidence in the west and uplift in the east. The relatively thicker Quaternary in the Manila Trench in the eastern margin of the SCS is mainly a result of tectonic compression resulting in sedimentary layers thicker and abundant provenance from Taiwan and the Philippines.