Objective To investigate the therapeutic efficacy of Erchen Decoction plus Sanzi Yangqin Decoction in the treatment of elderly patients with acute exacerbation of chronic obstructive pulmonary disease(COPD)of phlegm-dampness accumulation in lung syndrome,and to explore its possible therapeutic mechanism through the interleukin 33/soluble growth stimulation expressed gene 2(IL-33/ST2)signaling pathway.Methods A prospective trial was conducted on 92 elderly patients with acute exacerbation of COPD of phlegm-dampness accumulation in lung syndrome who were treated in Haikou Hospital of Traditional Chinese Medicine from January 2021 to June 2023.The patients were randomly divided into the control group and the observation group according to the random number table method,with 46 cases in each group.The control group was treated with conventional western medicine,while the observation group was treated with Erchen Decoction plus Sanzi Yangqin Decoction on the basis of treatment for the control group,and the course of treatment covered two weeks.The changes of traditional Chinese medicine(TCM)syndrome scores,lung function indicators,white blood cell count(WBC),neutrophil percentage(Neut%),and serum IL-33,ST2,interleukin 6(IL-6)and interleukin 8(IL-8)levels of patients in the two groups before and after the treatment were observed,and the clinical efficacy and medication safety of the patients in the two groups were evaluated.Results(1)After two weeks of treatment,the total effective rate of the observation group was 86.96%(40/46)and that of the control group was 67.39%(31/46),and the intergroup comparison(tested by chi-square test)showed that the therapeutic effect of the observation group was significantly superior to that of the control group(P<0.05).(2)After treatment,the TCM syndrome scores such as dyspnea,suppression in the chest,cough and expectoration in the two groups were decreased compared with those before treatment(P<0.05),and the decrease in the observation group was significantly superior to that in the control group(P<0.01).(3)After treatment,the lung function indicators such as forced vital capacity(FVC),forced expiratory volume in one second(FEV1),and peak expiratory flow(PEF)of the two groups all improved compared with those before treatment(P<0.05),and the improvement in the observation group was significantly superior to that in the control group(P<0.01).(4)After treatment,the levels of inflammatory indicators such as WBC,Neut%,and serum IL-33,ST2,IL-6 and IL-8 in the two groups were all decreased compared with those before treatment(P<0.05),and the decrease in the observation group was significantly superior to that in the control group(P<0.01).(5)The total incidence of adverse reactions in both groups was all 8.70%(4/46),and the intergroup comparison showed that the difference was not statistically significant(P>0.05).Conclusion The clinical efficacy of Erchen Decoction plus Sanzi Yangqin Decoction in the treatment of elderly patients with acute exacerbation of COPD of phlegm-dampness accumulation in lung syndrome is remarkable,and it is effective on improving the TCM syndromes,related inflammatory indicators and lung function.Its mechanism may be related to the reduction of the patients'serum IL-33 level,the inhibition of IL-33/ST2 signaling pathway and the expression of related inflammatory factors,so as to inhibit inflammatory response and improve the progression of COPD.