The distribution of dissolved manganese (DIMn) and manganese in surface sediment in the Sanggou Bay were investigated in April, August, October 2011 and January 2012. The concentrations of DIMn and manganese in surface sediment were measured by the the catalytic-kinetic spectrophotometric and two-step extraction method, respectively. The results showed that the average concentration of DIMn in 2011−2012 were (60.5±43.1) nmol/L in April, (42.0±30.5) nmol/L in August, (23.4±11.2) nmol/L in October and (18.2±13.5) nmol/L in January. The high concentrations of DIMn always being found in the estuary and decreased from nearshore to the coastal area. There exists significant seasonal variation for concentrations of DIMn with highest value in spring, followed by summer and autumn, and lowest value in winter. The concentrations of DIMn in the Sanggou Bay were higher than the Ailian Bay and the Lidao Bay in spring and summer, and with insignificant variation in autumn and winter. The average content of total manganese (TMn_s) in surface sediment were (861±308) mg/kg in April 2011, (915±322) mg/kg in August 2011, (589±108) mg/kg in October 2011 and (653±185) mg/kg in January 2012. The average content of acetic acid-soluble manganese (HAc-Mn) in surface sediment were (500±272) mg/kg in April 2011, (502±232) mg/kg in August 2011, (322±81) mg/kg in October 2011, (345±91) mg/kg in January 2012. The content of TMn_s and HAc-Mn in the sediment of the bay were both decreased with the increasing distance from the coast. There exists significant seasonal variation for concentrations of HAc-Mn in the surface sediments during the investigations, with higher concentrations occurred in spring and summer than that in autumn and winter. The adsorption of SPM and utilization of plankton were important factors affecting the content and distribution of DIMn in the Sanggou Bay. The major sources for DIMn in the Sanggou Bay included the inputs from riverine, groundwater discharge, atmospheric deposition and release from the sediment-water interface. The major sinks for DIMn included the output into the Yellow Sea and the absorption or accumulation by biological activities. A preliminary box model was established to estimate the budgets of DIMn for the Sanggou Bay, which demonstrated that in addition to output into the Yellow Sea and biological activities, there was other sinks of DIMns in the Sanggou Bay. The results provide basic data for further understanding the biogeochemical cycle of DIMn in the Sanggou Bay.