Abstract: Six acute severe asthma patients, whose average pH was 7.095 （ranged from 6.806 o 7.26）, PaO₂ 7.18 （3.4-10.7） kPa and PaCO₂ 11.0 （7.9-17.9） kPa, were treated by the combination of mechanical ventilation with conventional drug therapy. PEEP which from 0.5-1.8 kPa （5-18cmH20） was applied for all patients. The patients were weaned from mechanical ventilation at the time less than 24 hours （3 cases）, 48 hours （2 cases） and 5 days, respectively. Indication and parameters of mechanical ventilation for the treatment of acute severe asthma were discussed.