this paper deals with analysis of the red tide of Triclodesrzi in Dong Hai of China.,1972. The red tide was caused by species of Cyanaphyres,eviz Trclaadsm.iwmhiTdedti Gomant, Trichodesmium thibau.ii CTomont, Trirh.octesmizm tryh.PaumEhr. The dominant species was Tricociesmium hiZdehrrrrcitiz Clvruont. Intensive redtide was found in the area of in August AfterSeptember the area of distrivutivn of red tide expanded, and the center still is locs,tedin the same place. The located area was the food base of machercis, scads and. otherfish was damaged obviously by the red tide. The hioms of zoaplankton was decreasedrapidly and the migration route of mackerels and scsds was shifted, Thonlrh death offish did not happen, the red tide caused heavy drop of catch of m;ickere.ls and scalds,and in August no fish has been caught, The uptvelling eused by stronger cyeloniv vortex in summer 1972 arid continue-ing strong typhoons were nia,jvr factors for the formation of the red tide Besides, theappearance of high temperature in water provided favourtble condition for the bloomingof these tropical algae.