Structure of thermocline, characteristics of stability and intensity of vertical transfer have been studied with hourly oceanographic data in each layers on Line 207 from 1968 to 1969. It is found that a typical thermocline is formed at depths of 10 to 50 meters in summer and early autumn and its core is located near depths of 25 meters. The maximum diffusion coefficient of vertical turbulent is found to be 140$ extrm{cm}^2$/sec at the surface layer(i.e., 0-10 meters), while the minimum is 5$ extrm{cm}^2$/sec at depths of 25 meters, consistent with characteristics of stability and structure of thermocline layers. Our computed diffusion coefficient and stability indicate that the mixing hardly takes place below depths of 80 meters during summer and early autumn, but for the rest of the season mixing could move up to the depth of 50 meters. It appears that the Western Channel of the Korea Strait consist of three different water masses during summer and autumn, and for the rest of the season, two kinds are present.