The community structure of phytoplankton could be affected by environmental factors, such as water temperature, salinity, total nitrogen, and total phosphorus. Changes in environmental factors may be associated with alteration in the community structure of phytoplankton. To investigate the consequences of oil spill in the Bohai Sea in 2011, here we analyzed features of phytoplankton community structure using data obtained in the comprehensive investigation at 41 stations within the central Bohai Sea in May, July, November and December 2013. The sampling and measuring methods followed the Specifications for Oceanographic Surveys and Specifications for Marine Monitoring. A total of 87 phytoplankton species were found, including 72 species of diatom in 33 genera and 15 species of pyrrophyta in 9 genera. There was another species of chrysophyta in 1 genus. Diatoms were the dominant phytoplankton species, while some dinoflagellates species also accounted for a large portion in the community. Compared to the historical data in the same season, there was an obvious shift in the community structure. Eucampia zodiacus, a previous dominant species, were not found in this survey; however, Thalassiosira punctigera appeared for the first time as a dominant species. The dominance of planktonic dinoflagellate became increasingly evident. The average cell abundance was 200.14×104 cell/m3, 16.32×104 cell/m3, 7.43×104 cell/m3 and 12.77×104 cell/m3 in May, July, November and December respectively. The cell abundance in May was higher compared to the historical data probably due to the outbreak of Guinardia delicatula, and in other month it was relatively stable. The diversity index and evenness index of the community structure followed the order July > November > May > December. The Spearman analysis revealed that changes in the nutrient structure of the central Bohai Sea was responsible for the shift in community structure, and that the spilled petroleum also might have affected the community structure. Because the phytoplankton community structure was generally consistent with results from other investigations, it was most likely unchanged after the oil spill in 2011.