Abstract: Pyroclast is a kind of important sediment source to marginal seas and the distribution of it is of great significance to the study of sedimentation and tectonic activities. In this paper, the detrital components from 2276 surficial samples of the South China Sea are studied. Volcanic glasses are found in 664 sites, accounting for 29.17%, of which the maximum is as high as 95.8×10⁻³. The volcanic glasses mainly occur in the eastern part of the South China Sea and gradually decrease westward. The distribution pattern of the main heavy minerals, such as magnetite and hornblende, is similar to that of volcanic glasses, indicating that they may have the same origin. Data suggests that volcanic glasses are mainly sourced from the Philippine islands. It is consistent with the distribution pattern of active volcanoes widely distributed in the Luzon island and partial Ryukyu-Taiwan-Philippines volcanic arc and seismic zone along the eastern margin of the South China Sea. The Sumatra-Java volcanic arc and seismic zone in the southern margin of the South China Sea, although there are frequent Quaternary volcanic and seismic activities, does not contribute much volcanic glasses to the surficial sediments. Volcanoes in the South China Sea are not the main contributor and the northern and western parts of the South China Sea have almost contributed nothing.