Abstract： Objective To study the effectiveness and safety in bronchoscopy under anesthesia with fentanyl combined with midazolam.Methods We randomly allocated 132 patients(male 69,female 63,median age 62.9 years) requiring bronchoscopy in Beijing Xuanwu Hospital into 2 groups during January 2015 to December 2016.The trial group included 66 patients,receiving fentanyl combined with midazolam for anesthesia,while the control group of 66 patients receiving 2％ lidocaine for topical anesthesia.In the trial group,there were 37 males and 29 females,with a median age of 63 years (range 26-82).In the control group,there were 36 males and 30 females,with a median age of 62.8 years (range 30-82).The pulse,mean arterial pressure,and the oxygen saturation of the patients were recorded before anesthesia and 5 minutes after deep anesthcsia was reached.Changes of vital signs and adverse reactions during the bronchoscopy were also observed.Results The fluctuation of pulse (12.3 ± 2.3)/min,mean arterial pressure(5.9 ±2.2) mmHg(1 mmHg =0.133 kPa) and oxygen saturation(4.4 ± 1.3) ％ was lower in the trial group as compared to that of the control group,pulse(21.9 ± 1.8)/min,mean arterial pressure(7.1 ± 2.3) mmHg,oxygen saturation (13.3 ± 4.2) ％,P ＜ 0.001.Five minutes after anesthesia,the pulse (80.0 ± 11.9)/min,the mean arterial pressure (95.0 ± 9.7) mmHg and the oxygen saturation (90.0 ± 5.67) ％ of patients in the trial group were lower than those in the control group [pulse(90.3 ± 17.0)/min,mean arterial pressure (102.7 ± 12.4) mmHg,oxygen saturation (96.5 ± 3.0) ％],the differences being statistically significant(P ＜ 0.001).The trial group also showed smaller fluctuation,better tolerance,and fewer adverse reaction sthan the control group.Conciusion Fentanyl combined with midazolam is safe and effective in bronchoscopy with fewer adverse reactions,but its early effect on the vital signs should be monitored and stricter indications may be needed.