In order to study the moisture absorption of tobacco leaf during processing, the absorption characteristic curves of tobacco leaf under different relative humidities (in the range of 30% to 90%) and temperatures (60, 70 and 80 °C), respectively, were determined dynamically. The equilibrium moisture content of tobacco leaf was obtained on the basis of the absorption curve, and the curve of equilibrium moisture content was fitted by GAB model. The results showed that GAB model could better describe the equilibrium moisture content of tobacco leaf under high temperature and relative humidity. The predicted values quite agree with the test values with a correlation coefficient of 0.980.