Abstract: In order to know the hygroscopic property of tobacco leaf during processing, the effect of temperature and humidity of hot air on the moisture content and absorption rate of flue-cured tobacco, B2F, were investigated by simulating the ordering conditions in a thermohygrostatic chamber.The results indicated that the absorption rate of tobacco increased with the increase of temperature or humidity of hot air at initial stage.With the progressing of processing, higher air temperature would accelerate the absorption rate to approach zero;when the humidity of hot air was lower, the absorption rate of tobacco would go down to below zero, in that case the tobacco was dehumidified.