Aim To evaluate the clinical application of propofol in critical patients with mechanical ventilation.Methods 22 patients with mechanical ventilation after major operation were randomly divided into control group and propofol group patient in the propofol group were continually transfused with propofol by micro pump.Clinical manifestations, blood pressure, heart rate and the concentration of epinephrine (E) and norepinephrine (NE) in patients of both groups were observed.Results The patients in propofol group were all in sleeping state, while those in the control group had evidently higher blood pressure, heart rate and the concentration of epinephrine and norepinephrine after wearing of ventilator.There was a significant difference between the two groups (P