Investigation of dissolved organic carbon (DOC) and particulate organic carbon (POC) at 12 stations in Yantai Sishili Bay in May, August, and November of 1997 and March and May of 1998 showed that DOC concentrations varied from 1.14 mg/L to 5.35 mg/L; that the average values at all stations in each cruise varied from 1.52 mg/L to 2.12 mg/L; that POC concentrations varied from 0.049 mg/L to 1.411 mg/L; and averaged 0.159 mg/L to 0.631 mg/L in each cruise. Horizontal distribution of DOC was influenced by factors such as continental input, organism activity, temperature, aquiculture environment, etc. The higher POC concentration occurred along the coast. The vertical distribution of DOC and POC changed obviously in spring and summer, but not obviously in autumn and winter. DOC concentration was highest in summer and POC in spring; both were lowest in winter. The seasonal change of DOC was consistent with primary productivity seasonal variation, and that of POC was consistent with chlorophyll a seasonal variation. The seasonal change trend of the C/N ratio of dissolved organic matter was obvious, but the C/N ratio of particulate organic matter had no such trend. Investigation of dissolved carbon (DOC) and particulate organic carbon (POC) at 12 stations in Yantai Sishili Bay in May, August, and November of 1997 and March and May of 1998 showed that DOC concentrations varied from 1.14 mg / L to 5.35 mg / L; that the average values ​​at all stations in each cruise varied from 1.52 mg / L to 2.12 mg / L; that POC concentrations varied from 0.049 mg / L to 1.411 mg / L; and averaged 0.159 mg / L to 0.631 mg / L in each cruise. Horizontal distribution of DOC was influenced by factors such such as continental input, organism activity, temperature, aquiculture environment, etc. The vertical POC concentration occurred along the coast. The vertical distribution of DOC and POC changed obviously in spring and summer , but not obviously in autumn and winter. Both DOC were was in summer and POC in spring; both were lowest in winter. The seasonal change of DOC was consistent with primary productivity seasonal variation, and that of POC was consistent with chloroph The seasonal change trend of the C / N ratio of dissolved organic matter was obvious, but the C / N ratio of particulate organic matter had no such trend.