Byuseofthehydrodynamicmodel,theharmonicconstantsof8principaltidalconstituents(Q_1,O_1,P_1,K_1,N_2,M_2,S_2andK_2)areobtainedfortheEastChinaSea,andtheharmonicconstantofS_aiscalculatedbytwo-dimensionalinterpolation.Thecalculatedresultsagreewellwiththeobserveddataaroundthesea.TheharmonicconstantscanbeusedtopredictthetideintheEastChinaSea.Thecotidalchartsofthe9tidalconstituentsrevealtheirdistribution.