The complications of mechanical ventilation were analysed retrogradely in 82 cases with respiratory failure treated in ICU in recent 5 years. There were 48 males and 34 females ranging from 28 to 82 years of age (mean age: 57.1 +/- 16.8). In 82 cases, 6 cases had complications of barotrauma, 39 cases, of infections, 15 cases, of hypotension, 24 cases, of arrhythmia, 14 cases, of upper gastrointestinal hemorrhage and 10 cases, of multiple organ failure. The total incidence of complication was 76.8%. Exactly within three days of mechanical ventilation, the incidence of complication was 31.3%, while beyond three days, it was 87.9%. It was indicated that the mortality increased significantly in the cases with severe complications such as, multiple organ failure. The causes of all kinds of complications and their prevention as well as treatments were discussed.