Objective:To evaluate effects of muscle relaxant on treatment of severe asthma with mechanical ventilation by retrospective analysis. Methods:Forty-one patients with severe asthma treated by intubation and mechanical ventilation were divided into muscle relaxants group(muscle relaxants and traditional treatment)and non-muscle relaxants group(traditional treatment only). The blood gas analysis,airway pressure,extubation time,and hospitalization time were compared between two groups. Moreover,the extubation time and hospitalization time of the patients treated with muscle relaxants more than 48 hours or less than 48 h were analyzed. Results:Compared to the non-muscle relaxants group,the pH value and PaCO2 of arterial blood in muscle relaxants group were significantly improved(P < 0.05),the peak pressure of airway was significantly decreased(P < 0.05)2 h after muscle relaxants treatment. No difference was found in PaO2 between two groups. The hospitalization time was shorter in the non-muscle relaxants group(P < 0.05),while no difference was found in extubation time between two groups. Notably,when using muscle relaxants more than 48 h,both extubation time and hospitalization time were significantly increased. Conclusion:Muscle relaxants can rapidly improve the pH value,decreased the PaCO2 and peak pressure of airway in severe asthma patients after mechanical ventilation. However,they would increase extubation time and hospitalization time.