Gas turbines are one of the most important machines for producing power. According to the important place of these turbines and their expanded application in powerhouses, has been done a lot of efforts for increasing work cycle efficiency of gas turbines. According to increased air temprature in hot months of year, so was decreased air density and after that, external power of gas turbine. One of the most important guideline is increasing the efficiency of  gas turbines by cooling entrance air to compressor. One of the most basic methods for cooling entrance air to compressor is using of fogging system. In this article, was discussed about thermodynamical modeling in fogging coolig by using of drop model. At first, for accounting drops evaporation being a model by using of steam density different in drop level and the air of internal canal environment to compressor, then for accounting operational parameters of gas turbine, was provided a computer code and  after comparing their results with experimental data, has been obtained results for gas powerhouse called shahid Modhaj of Ahwaz.