Abstract: Based on historical records of red tides from 1952 to 2017, and according to the analysis of their temporal, spatial, and biological variation, the basic characteristics of red tides in Shandong coastal waters are studied with preventive countermeasures proposed. Non-toxic dinoflagellate blooms are frequently observed with a scale less than 10 km² in shandong coast waters. The incidence of red tides is high from May to September and most events occur in the Yellow River Estuary, midwest of Laizhou Bay, Changdao offshore waters, Sishili Bay, Donggang offshore waters, Jiaozhou Bay and the Qingdao coast. Compared with other species, Noctiluca scintillans is frequently found. However, new causative organisms have been identified and the proportion of toxic and biphasic red tides has also increased since 2000. In order to prevent red tides, the level of information monitoring should be improved, risk assessments carried out and comprehensive management of the marine environment promoted.