【Abstract】Objectiv: To provide a safe device for fiber opticbroncho scope (FOB) examination under during general anesthesia, a Y-shaped anti-overflow screw-threaded device was described in this paper. Methods: A total of 88 cases of patients needed to be checked with FOB were selected in this study and randomly divided into four groups (22 cases in each group): (1) Group A, endotracheal intubation; (2) Group B: endotracheal intubation + Y-shaped device; (3) group C: laryngeal mask; (4) group D: laryngeal mask + Y-shaped device. Patients in group A received endotracheal intubation during general anesthesia . Anesthesia was induced with midazolam (0.05mg•kg-1), propofol (2mg•kg-1), cisatracurium (0.15mg•kg-1) and fentanyl (2µg•kg-1) and maintained by infusion of propofol (6mg•kg-1) and fentanyl administration.Ventilation used a volume control mode with a tidal volume of 8-10ml kg-1. In Group B, anesthesia intubation and maintaination were the same as in group A. A Y-shaped anti-overflow screw-threaded device was connected between the reinforced pipe joint and screw-threaded pipe joint. In group C, anesthesia and ventilation was the same as in group A. For group D, anesthesia and ventilation was the same as in group B. Ordinary L-type joints were used both in group A and group C for controlling ventilation, ventilation was inhibited and replaced by fiberoptic bronchoscope intubation at the time of examination. While in group B and group D, treatment procedures were continued along with ventilation. Continuous monitoring of relevant indicators in patients was conducted before and during examination, following parameters were carefully recorded, including the number of patients with arrhythmia, heart rate variation (HR) > 100 or < 60 beats/min cases, pulse oxygen saturation (SpO2) < 95% cases and noninvasive blood pressure (NIBP) fluctuations > 20mmHg cases, as well as the average examination time (min), and cases requring interruption of examination. In addition to the above indexes, mean airway pressure was recorded in group B and group D before and during the examination. Results: Arrhythmia cases of group B (2 cases) and group D (1case), HR changes cases of groupB（3cases）and group D (2 cases); SPO2<95% cases of group(1 case) and group D (1case): NIBP fluctuation >20mmHg cases of group B （2cases）and group D (1case). The mean time of examination in group B was 8.12min, that in group D was 8.00min, the difference between group B,D and group A,C has statistical significance (P < 0.05). EIther before or during the examination,the difference of arrhythmia, HR changes, SPO2<95%, NIBP fluctArrhythmia cases of B (2 cases) and group D (n = 1), HR changes the number of cases of B3) and group D (2 cases); SPO2<95% B the number of cases (1 case), group D (n = 1): NIBP fluctuation >20mmHg cases number B cases number 2 cases in group D (n = 1). The mean time of examination in group B 8.12min, group D 8.00min, B, D and C a group, the difference has statistical significance (P < 0.05). B, D two groups before the examination and check the number of arrhythmia, the number of cases of HR amplitude changes, the number of cases of SPO2<95%, the number of NIBP fluctuations in the number of >20mmHg is not statistically significant (p>0.05). The mean airway pressure in the groups was statistically significant (p<0.05) before and during the examination in the two groups. Conclusion the use of anti overflow pipe three way joint can be used in the treatment of patients do not stop the oxygen supply of oxygen treatment operation, especially with the use of laryngeal mask airway pressure changes in a small, convenient and safe.p>0.05). The difference of the mean airway pressure between group B and D was statistically significant (p<0.05) before and during the examination .Conclusion: The device of Three - way connector of anti - overflow - gas - threaded pipe can be applied to patients undergoing ventilation, leading to decreased airway pressure especially combined with laryngeal mask, which is convenient and safe. Conclusion the use of anti overflow pipe three way joint can be used in the treatment of patients do not stop the oxygen supply of oxygen treatment operation, especially with the use of laryngeal mask airway pressure changes in a small, convenient and safe.