Abstract: Objective: To investigate the effect of adjusting the relative humidity of drying medium on the drying characteristics and quality of ginger slices during hot air drying. Methods: To study the drying characteristics, color, shrinkage, rehydration, effective diffusion coefficient of moisture, curcumin and total flavonoid contents of ginger slices under the drying conditions of 60 ℃, 3.0m/s air velocity, constant humidity (RH of 15%, 25%, 35%, 45%) and phase humidity reduction (RH45% was kept at 15% for 10, 20, 30 and 60 min, respectively). total flavonoid content. Results: Under the condition of constant humidity, the drying time of ginger slices was prolonged with the increase of relative humidity; under the condition of stage humidity reduction, the drying time of ginger slices showed a tendency of decreasing and then increasing with the prolongation of the holding time of high relative humidity, and the drying time was shortened by 8.3% when the RH was kept at 45% for 20 min and then reduced to 15% after 30 min compared with that of the constant humidity (RH of 15%). The drying process of ginger slices was divided into ascending and descending. The drying process of ginger slices was divided into two phases of ascending and descending, and the moisture Deff varied in the range of 5.21×10⁻¹⁰~6.66×10⁻¹⁰ m²/s. The rehydration of ginger slices was the best, and the color difference value and shrinkage were the smallest when RH45% was kept at 20min and then decreased to 15%, and the difference was significant compared with that of constant humidity (P<0.05); the difference of RH45% was significant compared with that of constant humidity (P<0.05); the time required to complete drying was 8.3% shorter than that of constant humidity (RH of 15%) when RH45% was kept at 20 min and then decreased to 15%. After RH45% was kept for 30 min and then decreased to 15%, the content of curcumin and total flavonoids in ginger slices was significantly higher than that of constant humidity. Considering the drying time, color difference, shrinkage, rehydration, curcumin and total flavonoids content of ginger slices, it was concluded that the highest comprehensive score of ginger slices was 0.76±0.08 when RH45% was kept at 15% for 30 min, which was the optimal drying process. Conclusion: In the initial stage of hot air drying of ginger slices, keeping higher humidity of drying medium and maintaining it for a suitable time can accelerate the drying rate, shorten the drying time, and have better quality. The application of the phase humidity reduction and regulation strategy to the hot air drying process of ginger slices provides important theoretical support and technical guidance for the ginger processing industry.