Abstract: The characteristics of the green tide disaster occurred in the offshore area of east Shandong Peninsula are added up due to the monitoring data from 2008 to 2013.It indicates that the green tide disaster occurred every year in the offshore area of east Shandong Peninsula since 2007, mostly during May to August, with the most serious period from mid-June to mid-July.The principal causing species of the green tide disaster is Enteromorpha prolifera,which is exogenous and comes from the southern offshore area of Shandong Peninsula.The middle coastal area of the east Shandong Peninsula suffered most,especially the coastal area of Qingdao.