This study aims to investigate the hot air drying characteristics of Astragalus slices, and the kinetics of the drying process. The hot air drying experiment was conducted with hot air temperature, air velocity and slice thickness as experimental factors. The hot air temperatures are 40, 50 and 60 ℃ with the air velocities of 0.4, 0.8 and 1.2 m/s, and slice thicknesses are 3, 6 and 9 mm, respectively. The effects of them on the hot air drying curves, effective moisture diffusivity coefficient, rehydration performance and color difference of Astragalus slices were investigated respectively. The Weibull distribution was used to fit experimental data and the activation energy of hot air drying of Astragalus slice was calculated. The result shows that the drying process of the slices follows Weibull distribution (R2=0.995 1~0.999 2), and thus has a falling drying rate which indicates that the hot air temperature and the slice thickness have a great influence on the drying time. The effective moisture diffusivity coefficients found in this study ranged from 0.321×10 7 to 1.178×10 7 m2/s, greatly affected by the hot air temperature and slice thickness. The drying activation energy is 56.49 kJ/mol, which shows that drying process is relatively easy to operate. The rehydration ratios of Astragalus slice dry products are between 2.02 and 2.43, which have a negative correlation with hot air temperature and a positive correlation with slice thickness. The color difference SymbolDA@E is between 1.96 and 7.01, which increases with increasing hot air temperature and air velocities and decreases with increasing slice thickness. This study can provide a theoretical basis for the research and application of Astragalus hot air drying technology.