Objective To explore the application effect of different doses of Formoterol in moderate to severe chronic obstructive pulmonary disease(COPD).Methods A total of eighty-four moderate and severe COPD patients admitted to Fengcheng People′s Hospital from June 2019 to June 2020 were selected as the research subjects and divided into group A(42 cases)and group B(42 cases)by random number table method.Group A was treated with conventional dose of Formoterol,and group B was treated with double dose of Formoterol.The lung function(forced expiratory volume in the first second[FEV1]and FEV1 as a percentage of predicted value[FEV1%]and FEV1/forced vital capacity[FVC]),endothelial function(vascular endothelial growth factor[VEGF]and endothelin-1[ET-1],nitric oxide[NO])and the total incidence of adverse reactions of two groups were compared.Results Before and after treatment,there were no significant differences in FEV1,FEV1% and FEV1/FVC between the two groups(P＞0.05).After treatment,FEV1% and FEV1/FVC levels in both groups were higher than those before treatment,with statistical significance differences(P＜0.05).Before and after treatment,there were no significant differences in VEGF,ET-1 and NO between the two groups(P＞0.05).After treatment,the levels of VEGF,and NO in both groups were higher than those before treatment,ET-1 level was lower than that before treatment,the differences were statistically significant(P＜0.05).The total incidence of adverse reactions in group B was higher than that in group A,and the difference was statistically significant(P＜0.05).Conclusion Formoterol treatment for patients with moderate to severe COPD has significant therapeutic effects.Large doses of Formoterol will increase the incidence of adverse reactions.