In this article, using tidal differential equation, the gradients of the tidal levels were calculated with the data of tidal current in the sea；and then the tides in the sea have also been predicted by means of the tidal data at the coastal station. Simultaneously, the quasi-maximum velocity of tidal current, the energy imported into the East China sea by the sum of the M2 and S2 of the main semidiurnal constituent and its dissipation have been caleulated. In addition, the tide and tidal current properties,the propagation of the tide waves, quasi-maximum velocity of tidal current and the transport of the tidal energy have also been discussed.