Objective To explore the effect of Erchen Decoction and Sanzi Yangqin Decoction on thoracic and pulmonary compliance and gas exchange parameters in the treatment of phlegm dampness blocking lung syndrome of chronic obstructive pulmonary disease.Methods A total of 80 patients with phlegm dampness blocking lung syndrome of chronic obstructive pulmonary disease treated in Jiujiang Third People′s Hospital from January 2020 to January 2022 were selected as the research objects.The patients were divided into control group and observation group by random number table method,with 40 cases in each group.The patients in the control group were treated with conventional symptomatic Western medicine,and the patients in the observation group were treated with Erchen Decoction and Sanzi Yangqin Decoction on the basis of the control group.The symptom relief time,serum inflammatory factors,thoracopulmonary compliance indexes,gas exchange parameters,quality of life score,and incidence of adverse reactions were compared between the two groups.Results The remission time of all symptoms in the observation group was shorter than that in the control group,the difference was statistically significant(P<0.05).The levels of serum C-reactive protein,procalcitonin,interleukin-6 and tumor necrosis factor-α after treatment in the observation group were lower than those in the control group,the differences were statistically significant(P<0.05).The total chest and lung compliance,thoracic compliance,lung compliance,forced breathing volume in one second,forced breathing volume/vital capacity ratio and quality of life score after treatment in the observation group were higher than those in the control group,the differences were statistically significant(P<0.05).There was no statistically significant difference in the total incidence of adverse reactions between the two groups(P>0.05).Conclusion Erchen Decoction combined with Sanzi Yangqin Decoction can alleviate the symptoms of patients with phlegm dampness blocking lung syndrome of chronic obstructive pulmonary disease,reduce the inflammatory reaction in the patient,improve the chest and lung compliance and lung ventilation function,and improve the quality of life,with no increase in adverse reactions and good drug safety.