Particulate Organic Carbon (POC) in seawater is the basic variable of the marine carbon cycle and plays a key role in the study of the marine carbon cycle. The temporal and spatial variation of POC concentration in the South China Sea is analyzed and discussed based on the POC data set retrieved from the remote sensing data from 2003 to 2020. The results show that the annual average concentration of POC varies from 76.98 to 83.91 mg/m³ in the whole study area. The POC concentration distribution is high in the nearshore and low in the open sea. The POC concentration in the nearshore and shallow waters of the South China Sea is mainly affected by landbased input and coastal current, and the POC concentration in the open sea area is mainly controlled by the circulation and water mass of the South China Sea. The average POC concentration from the first quarter to the fourth quarter is 89.62, 72.90, 79.22 and 84.86 mg/m³. The POC concentration is low in summer and high in winter. The main reason is that the South China Sea is affected by the northeast monsoon in winter and the southwest monsoon in summer, which affects the seawater mixing layer structure in the South China Sea, and phytoplanktons are more prosperous in winter than in summer. On the monthly scale, the POC concentration is the highest in January; the POC concentration decreases rapidly from February to April and reaches the lowest in May; From June to December, the POC concentration begins to rise slowly. The conclusions will provide the decision-making basis for the goverment to deal with such issues as the carbon cycle, carbon peak and carbon neutralization, blue economic development, offshore ecological protection and cope with climate change in the South China Sea.