Abstract: The dissolved and particulate organic carbon (POC) at Yellow River estuary are studied by 4 cruises of April and September 2004, Septenber 2005 and April 2006, and simultaneously and consecutively measured in August 2003.The result indicates that POC in the total suspended sediment (TSS) is about 0.51% without variations from dry weather to wet one.With this uniformity, POC values are correlated well with the concentrations of the total suspended matter.Due to the terrestrial TSS dilution, the contribution of autochthonous POC to total POC appears when TSS < 200 mg/L,Φ<16μm portion of TSS increases in the composite particles, which causes the decrease of median size-particles after precipitation of particles, and the percentage of POC increases with the decrease of the particles size.More than 80% POC concentrates on particles with Φ<16μm, and POC in particles with Φ<32μm account for 95% flux from the Yellow River estuary to Bohai sea.65% of the total POC will be settled with the precipitation of particles in the maximum turbidity zone (MTz).When TSS=455 mg/L, the ratio of DOC/POC is 1.A linear distribution of DOC versus salinity are observed when S > 10 both in dry and wet weather, but the input of DOC in the sediments desorption process, when S < 10 range, will make DOC's effective concentration 10% and 20% higher respectively than in situ freshwater in dry and wet weather.