The vertical structure of the water temperature in the Bohai Sea, Yellow Sea and East China Sea shows some hydro-physical characteristics which can only be found over the continential shelves in shallow sea. Its distribution and variation appear to be more complicated. We have made the descriptive statistic analysis based on observational data (1975-1980) offered by National Bureau of Oceanography. This paper consists of three aspects: (1) the distribution of the relative frequency of the value of the thermal gradient (divided by absolute value equals to or greater than 0.1℃/m) ; and (2) the horizontal plane distribution of the water temperature as distinguished from its type; ,and (3) the discussion of three characteristic values of thermocline under its generation, development, powerful and prosperous, and decline processes.