Nowadays, in consideration of environmental issues and limitation of fossil fuels, there is a particular consideration of renewable energy including Ocean Energy, that can extracted going through various methods such as Wave Energy, Tidal Energy, Salinity Gradient, OTEC: Ocean Thermal Energy Conversion.Herein this research, operation of OTEC Method in Southern Caspian Sea has been discussed. For this purpose Sea Surface Temperature (SST) Data and Thermocline diagram with respect to 25 stations from east to west coastal area, measured in 1995 in various seasons, have been used. Considering the researches conducted, in order to use OTEC, there must be a difference in temperature between the surface and depth for at least 20 Degrees Centigrade. If such difference in temperature occurs in less depth, closer to the coast, such energy extraction will be more cost-effective.According to investigations conducted, there is a difference in temperature for about 20 Degrees Centigrade in the depth of about 200 m in the Caspian Sea during hot seasons of the year. In summer and early autumn when Thermocline achieves its complete growth, energy extraction from OTEC has a desirable yield. During winter and spring when there is decay in Thermocline, the yield is so low that using this method is not justifiable. Thus, this method can only be used in hot seasons of the year. Finally, hydrographic and temperature investigations have revealed that southeastern coasts especially those of Bandar Neka and Babolsar achieve the desirable difference in temperature, closer to the coast due to high SST and coastal slope, compared to other areas and eventually, using OTECT is cost-effective.