Abstract: In order to study the thermodynamic properties of the fried banana chips, understand the water and energy change in the adsorption process, sorption isotherms of fried banana chips were determined using the gravimetric static method at the temperatures of 10, 25, 40℃ and 6 different water activities.6 kinds of adsorption model were used to the fitting analysis.The results showed that the most suitable models were the Peleg and GAB model, and the monolayer moisture content was obtained from GAB model.Using the thermodynamic equation, the isosteric heat and differential entropy under conditions of different water content could be obtained, the results showed that the isosteric heat and differential entropy were determined to be decreasing as moisture content increasing.