Abstract: Seawater samples were collected from the northern South China Sea in June 2015 to study spatial distributions of total dissolved carbohydrates(TCHOs) constituents, including dissolved monosaccharides(MCHOs) and polysaccharides(PCHOs). The concentrations of TCHOs, MCHOs and PCHOs were measured with TPTZ(2, 4, 6-tripyridyl-s-triazine, C₁₈H₁₂N₆) method. The results showed that the horizontal distributions of TCHOs, MCHOs and PCHOs displayed a decreasing trend from inshore to offshore sites and high concentrations mostly appeared in inshore sites which were influenced evidently by anthropogenic activity. Based on the study of the transect S in the east of the Pearl River estuary, seawater in this area was significantly stratified, and the vertical distributions of TCHOs, MCHOs and PCHOs were similar. Moreover, the concentrations of TCHOs, MCHOs and PCHOs of the seawater in the upper layer were higher than those in the lower layer, and the maxima of TCHOs, MCHOs and PCHOs appeared in the upper layer. In addition, the concentrations at some stations were influenced evidently by the Pearl River diluted water. The distributions of Chl a and dissolved organic carbon(DOC) were similar to those of TCHOs, MCHOs and PCHOs. However, the horizontal distributions of Chl a and salinity were more similar and there was no high value for the vertical distributions of Chl a and DOC under the euphotic layer. At the same time, the results also showed that the distributions of Chl a and DOC had a great influence on the distribution of TCHOs, MCHOs and PCHOs.