Abstract: OBJECTIVE To investigate the efficacy of different drying methods of ethyl alcohol rinsing and compressed air and drainage with sterilized syringe on gastrointestinal endoscope disinfection by microbiological surveillance. METHODS Stratified random sampling and double-blind (reprocessing operator and laboratory technician ) trial were conducted,the enrolled gastrointestinal (GI) endoscopes were randomly assigned to 3 groups after standard process including pre-cleaning, cleaning, rinsing, disinfection and final rinsing by professional. Group A(n=99) had no drying, group B(n=96) was dried with compressed air for 30 seconds to every channel, and group C(n=105) was flushed with 30ml of 75% ethyl alcohol for 3 min, then all channels were rinsed with compressed air for 30 seconds. The microbiological surveillance were performed by a laboratory technician, which used 10ml neutralizer to flush the biopsy channel, collected the sample and inoculated on plain agar under an aseptic procedure for 48h at 35℃, then the colony forming units(CFU) were counted. RESULTS The data of CFU in 3 groups were skewed distribution. The P₇₀,P₈₀ and P₉₀ of CFU in Group C were lower than those of the other two groups, and the difference was significant(P<0.05). The microbiological qualification rates of all endoscopes in group A, B and C were 73.73%, 77.08% and 89.5%, the qualification rate of group C was higher than that of group A, and the difference was significant(P<0.05). There was no significant difference in the microbiological qualification rates of gastroscope after three kinds of interventions, and the microbiological qualification rates of enteroscopy after three kinds of interventions were 45.71%, 54.28% and 88.37%, and the difference was significant(P<0.05). A total of 86 strains of pathogenic bacteria were detected, including 17 strains of gram-negative bacteria, with the detection rate of 5.67%, 68 strains of gram-positive bacteria, with the detection rate of 22.67%, and 1 strain of fungi, with the detection rate of 0.33%. CONCLUSION Drying endoscopes after disinfection with 75% ethyl alcohol can improve the efficacy of endoscope reprocessing, and drying with alcohol is superior to compressed air or drainage with syringe.