Abstract: Objective To investigate the effective and safe depth of endotracheal suction for elderly patients with trachea intubation.Methods Sixty elderly patients with pulmonary infection underwent mechanical ventilation were randomly divided into shallow suction group (tracheal suc-tion tube over the cannula 2 cm)and depth suction group (tracheal suction tube into airway 2 cm away before insertion resisted),with 30 cases respectively.The changes in heart rate,systolic pres-sure,respiratory rate and oxygen saturation was measured before and after suction.Comparison was also made on interval time of suction,suction frequence and airway injury between two groups.Re-sults There was no significant difference in changes of heart rate,systolic pressure and respiratory between two groups(P >0.05).After endotracheal suction,there was a significant difference in growth of oxygen saturation between two groups (P <0.05).Compared with shallow suction group,depth suction group has longer interval time and less frequency(P <0.05).Conclusion There was no significant difference between shallow and depth endotraheal suction for elderly pa-tients with trachea intubation,well-designed studies is wanted to explore the effective depth of en-dotraheal cannula.