The effects of air temperature and relative humidity (RH) on the drying kinetics of two flue-cured tobaccos (C3F and B3F) were studied with a thermogravimetric device for drying analysis in this work. The drying experiments were carried out with the drying air temperature of 60℃, 70℃, 80℃ and 90℃ and the RH of 0%, 10%, 20%, 30% and 40% at a constant airflow. A modified Arrhenius-type equation of diffusivity considering the effect of RH was proposed. By comparison with five thin-layer drying models and five equilibrium moisture content models to describe the drying kinetics of tobaccos samples, the high coefficient of determination (R2) and low reduced chi-square (χ2) and residual sum of squares (RSS) indicated that the Logarithmic model and the Modified Oswin model appeared to be the most suitable for predicting moisture ratio and the moisture desorption relationship of tobacco samples. The effective moisture diffusion coefficient under different temperatures and RHs ranged from 1.68×10-11 m2/s to 6.81×10-11 m2/s for C3F and from 1.62×10-11 m2/s to 6.68×10-11 m2/s for B3F. The modified Arrhenius-type equation with a RH term was found to be effective for describing the drying behavior of two flue-cured tobaccos and the activation energy (Ea) is 34.636 KJ·mol-1 and 35.2 KJ·mol-1 for C3F and B3F respectively.