Objective:To study effects of Propofol on arterial blood gas,airway resistance and pulmonary function of post-operation patients with severe hypercapnic respiratory failure for sedation during mechanical ventilation.Methods:Forty-four cases of post-operation patients with severe hypercapnic respiratory failure were divided into two groups.control group(n=22):patients receive midazolam 10²0mg i.v,Propofol group(n=22):receive Propofol 0.5².0mg/(kg.h) i.v.The comparison was made on the changes of pH,PaO2,PaCO2 in the arterial blood gas before and after the treatment 1/2h,1h,between the two groups.And also the changes of Pmax,Ppalt,PEF,FEV1/FVC in pulmonary function between the two groups.Results:Significant differences were found in the Propofol group of the improvement of pH,PaO2,PaO2/FiO2,PEF,FEV1/FVC in pulmonary function and the decreased value of PaCO2,Pmax、Ppaltbefore and after the treatment,compared with the control group(P<0.05⁰.01).Conclusions:Propofol infusion had an excellent effect for sedation in post-operation ventilation patients with severe hypercapnic respiratory failure,could decrease airway resistance,improved the oxygenation in lung,Also could maintain the coordination between spontaneous breath and mechanic ventilation.