Tidal harmonics of 8 principal constituents (M2, S2, K1, O1, N2, K2, P1 and Q1)derived from ground observations at 152 tidal gauge stations are used to assess the accuracy of 7 global ocean tidal models. It is shown that for the deep ocean area these models have high accuracy. The root-mean-square values of tidal height differences (RMSd) are within the range from 1.0 to1.3 cm for M2, and the rootsumsquare values of the RMSd of these 8 constituents lie in the range from 2.0 to 2.3 cm. Comparison of the global tidal models to 18 offshore and island tide gauge observations in the seas adjacent to China shows that the accuracy significantly decreases. The RMSd values of constituent M2 lie in the range of 4.4 to 10 cm, which is significantly greater than that in the deep ocean area. Among these models, the model NAO99 that assimilates T/P altimeter data and tide gauge observations into a hydrodynamic model, developed by the National Astronomical Observatory of Japan, has the best accuracy for the seas adjacent to China.