Objective To study the influencing factors for duration of mechanical ventilation in chronic obstructive pulmonary disease ( COPD) patients with type II respiratory failure. Methods Twenty-eight cases of mechanical ventilated COPD patients with type II respiratory failure were enrolled from March 2006 to March 2008 in Beijing Shunyi Hospital. They were divided into two groups based on their duration of ventilation: ≤7 d group as group I, and gt; 7 d as group II. Data of heart rate and blood pressure were recorded before the trachea intubation. Clinical data of blood routine, blood gas analysis and serum biochemistry were collected and analyzed. Previous history, smoking history and subsequent complications were also recorded. Results Heart rate in the group II were significantly higher than which in the group I[ ( 121. 50 ±17. 20) /min vs ( 103. 08 ±19. 97) /min, P lt;0. 05] . The incidences of upper gastrointestinal hemorrhage and blood pressure fall immediately after intubation were 63% and 88% respectively in the group II, which were significantly higher than the group I ( 0 and 25% ) . The levels of albumin, pre-albumin, Na+ , PaO2 were ( 29. 06 ±5. 00) g /L, ( 66. 36 ±17. 72) mg/L,( 138. 45 ±4. 74) mmol /L and ( 49. 06 ±20. 11) mm Hg respectively in the group II. While in the group I, those were ( 37. 11 ±2. 73) g /L, ( 127. 70 ±35. 84) mg/L, ( 143. 29 ±3. 42) mmol /L and ( 72. 25 ±38. 69) mm Hg respectively, which showed significant differences compared with the grouop II. The incidence of previous concomitant cerebral infarction showed significant difference between the group I and group II( 33. 33% vs 0) .Conclusion The levels of albumin, pre-albumin, heart rate before the intubation, upper gastrointestinal hemorrhage and blood pressure fall immediately after the intubation are associated with duration of mechanical ventilation and may indicate the prognosis in COPD patients with type II respiratory failure.