Abstract: Exergy analysis was conducted to analyze the performance of the medium temperature closed-loop heat pump drying system for the fire hose with R134a as refrigerant. Through experiments,the changes of COP,specific moisture extraction rate,exergy loss and exergy efficiency of the system at different air supply temperatures were studied to determine the optimal drying conditions of the system.The results show that as the drying temperature increases,the drying time gradually become shorter,the system coefficient of performance gradually decreases,and the overall exergy loss gradually decreases,and exergy efficiency increases. When the drying temperature is 65 ℃,the total power consumption of the system reaches the minimum value of 3.01 kWh. At this point,the specific moisture extraction rate（SMER）reaches the maximum value,which is 0.537 kg/kWh. Overall exergic efficiency reaches the maximum of 44.2% at 60 ℃,87.3% higher than the lowest exergic efficiency at 40 ℃.