Abstract: Heat pump treatment and hot- air treatment were separately applied to the drying of Pericarpium Citri Reticulatae( PCR). The study was executed to investigate the effect of temperature and velocity of air medium( VOAM) on the drying characteristics,shape changes and main nurtritional components( volatile oil,hesperidin) of PCR in a certain environment relative humidity.Meanwhile,influences of both drying methods on quality of treated samples were also compared. The experimental results showed that less time was taken to acquire the same moisture products under heat pump drying.In addition,products which were dried by heat pump dehumidifier,with small shrinkage,contain high- content volatile oil and hesperidin. Analysis of variance revealed that temperature was the main factor affecting the drying rate.Heat pump drying technology was optimized,when the environmental relative humidity was 70%,and acquired parameters for drying PCR were as followed : relative humidity was 40%,drying temperature 60 ℃,VOAM 1.5 m / s and the drying time about 2.25 h,the value of shrinkage rate was 35.3%,the content of volatile oil and hesperidin respectively were 1.692 mg /100 m L and 1.085 mg /100 m L.