Objective To observe the efficacy and safety of adjuvant therapy with Yiqi Ditan Tongfu Decoction（益气涤痰通腑汤）for chronic obstructive pulmonary disease（COPD）patients complicated by respiratory failure with difficulty in weaning off ventilator. Methods Totally 195cases of COPD complicated by respiratory failure with difficulty in weaning off ventilator were randomized into the treatment group of 100cases and control group of 95cases.Both groups were given symptomatic and supportive treatment such as mechanical ventilation

antispasmodics

expectorants

catharsis and anti-infection.The treatment group was added with nasogastric administration of Yiqi Ditan Tongfu Decoctiontwice daily.The rapid shallow breathing index（RSBI）

self-tidal volume（sTv）and maximum inspiratory pressure（MIP）were observed before and on the 6th

12th day of the treatment in both groups

and the numbers and success rates of weaning off ventilator were recorded in both groups.The adverse reactions were observed. Results The success rates of weaning off ventilator on the 6th and 12th day of treatment were 40.00%and 78.00%in the treatment group

which were significantly higher than 21.05%and 43.16%in the control group.The RSBI

sTv and MIP were significantly improved on the 6th and 12th day of treatment in the treatment group（P<0.05or P<0.01）.The RSBI was significantly decreased on the 6th and 12th day of treatment but the sTv and MIP were significantly increased on the 12th day of treatment in the control group（P<0.05or P<0.01）.Comparing with the control group

the RSBI

sTv and MIP were significantly improved on the 6th and 12th day of treatment in the treatment group（P<0.05or P<0.01）. Conclusion The adjuvant therapy with Yiqi Ditan Tongfu Decoctionis effective for COPD patients complicated by respiratory failure with difficulty in weaning off ventilator.It can obviously increase the success rate of weaning off ventilator and improve the ventilation function.