Abstract: Concentrations of monosaccharides (MCHO), polysaccharides (PCHO) and total dissolved carbohydrates (TCHO) were measured with 2, 4, 6-tripyridyl-s-triazine (TPTZ) method in the seawater of the South Yellow Sea and the East China Sea during spring.Our results showed that the concentrations of dissolved carbohydrates in South Yellow Sea were higher than those in the East China Sea.Moreover, distributions of MCHO, PCHO and TCHO at transect B of the South Yellow Sea and transect P of the East China Sea were investigated.The results indicated that the vertical distributions of MCHO, PCHO and TCHO at transect B displayed decreasing trend from inshore to offshore sites as well as from surface seawater to bottom seawater.In contrast, the vertical distributions of MCHO, PCHO and TCHO at transect P did not show similar trend due to the influences of the Changjiang diluted water, Taiwan warm current and Kuroshio.The results of diel variations at station E2 suggested that high peaks of MCHO, PCHO and TCHO appeared from 12:00 to 18:00 and low peaks appeared from 4:00 to 8:00.In addition, TCHO was positively correlated with PCHO, and MCHO had no correlation with PCHO.However, MCHO peaks lagged behind PCHO peaks, which might be because PCHO was decomposed to release MCHO by breaking the glycoside bond.