A finite element model, QUODDY model, is used to study the tides in the East China Sea, the Yellow Sea and the Bohai Sea in this paper. The simulation results fit well with the observation data. The cotidal charts of M2, S2, K1, O1 and M4 are given out. The result of this paper supports that the phase-lag of M2 varies little at Laizhou Bay. The amphidromic point of M2 disappears in the Liaodong Bay when the bottom stress drag coefficient increases to 0.0028. There is a high amplitude (more than 0.06m) region of M4 around (32.8