OBJECTIVE： To investigate the effects of sufentanil combined with dexmedetomidine on ICU acquired weakness （ICU-AW） of AECOPD patients receiving mechanical ventilation. METHODS： A total of 120 AECOPD patients in ICU of our hospital during Oct. 2015-Oct. 2016 were divided into group A and B according to random number tablet， with 60 cases in each group. Group A was given analgesia and sedation of sufentanil combined with propofol； group B was given analgesia and sedation of sufentanil combined with dexmedetomidine. RAAS sedation score and British Medical Research Committee （MRC） score were compared between 2 groups before treatment and 7 d after treatment. The incidence of ICU-AW， delirium and tracheal extubation were observed. The staying time in ICU， total hospitalization time and the occurrence of ADR were compared between 2 groups after diagnosed as ICU-AW. RESULTS： After treatment， the scores of RASS sedation degree scale in 2 groups were decreased significantly compared to before treatment， with statistical significance （P＜0.05）； there was no statistical significance between 2 groups （P＞0.05）. MRC score of group A was decreased significantly compared to before treatment， and significantly lower than group B， with statistical significance （P＜0.05）. There was no statistical significance in MRC score of group B before and after treatment （P＞0.05）. After 7 d of treatment， the incidence of ICU-AW in group B  was significantly lower than group A （40.00％ vs. 56.67％）； the incidence of tracheal extubation in group B was significantly higher than group A （70.00％ vs. 53.33％）， the incidence of delirium was significantly lower than group A （13.33％ vs. 20.00％）； the staying time in ICU and total hospitalization time in group B after diagnosed as ICU-AW were significantly shorter than group A， with statistical significance （P＜0.05）. There was no statistical significance in the total incidence of ADR between 2 groups （P＞0.05）. CONCLUSIONS： Compared with sufentanil combined with propofol， sufentanil combined with dexmedetomide shows similar analgesia and sedation effect， but has better influence on the muscle strength of the patient， reducing the incidence of ICU-AW and delirium， shortening the duration of mechanical ventilation， staying time in ICU and total hospitalization time in AECOPD patients receiving mechanical ventilation， with similar safety.