With the results of numerical modelling of the tide and tidal current this paper discusses the characteristics of tidal mixing in the Bohai Sea, the Yellow Sea and the East China Sea which shows that in the area with significant diurnal tidal current the Simpson-Hunter stratification parameter K, calculated by using quasi-maximum current speed rather than amplitude of M2 constituent tidal current can represent better the characteristics of tidal mixing. Analysis of the relation of the distributions of the bottom cold water (Yellow Sea Cold Water Mass) in the cooling season with tidal mixing showed that the bottom cold water can exlst longer in the northern and southern weak tidal mixing sreas of the Yellow Sea than other areas because of minimum tidal stirring there. The efficiency of wind and tidal mixing in the western part of southern Yellow Sea are also discussed.