Abstract: OBJECTIVE To study the effect of levofloxacin combined with inhalation of large dose ambroxol injection by oxygen on levels of serum Apolipoprotein E(ApoE) and procalcitonin(PCT) of elderly patients with chronic obstructive pulmonary disease (COPD) complicated with pulmonary infections.METHODS 86 elder patients with COPD complicated with pulmonary infections in our hospital from January 2016 to June 2017 were selected as the subjects. The patients were randomly divided into the group A(n=29 cases), group B(n=29 cases) and group C(n=28 cases). The group A was treated with levofloxacin combined with ambroxol hydrochloride intravenous drip, the group B was treated with levofloxacin combined with ambroxol hydrochloride 30mg oxygen inhalation, and the group C was treated with levofloxacin combined with ambroxol hydrochloride 60mg oxygen inhalation, then the clinical indexes were compared.RESULTS There were no significant differences in WBC, PCT, hs-CRP and ApoE among the three groups before the treatment (P＞0.05). The WBC, PCT, hs-CRP and ApoE of the group B after the treatment were significantly lower than those of the group A, and the WBC, PCT, hs-CRP and ApoE of the group C after the treatment were significantly lower than those of the group A and group B(P＜0.05). The absorption time of lung infection focus and hospital stay of the group B were significantly lower than those of the group A, and the absorption time of lung infection focus and hospital stay of the group C wereHT5"SSsignificantly lower than those of the group A and group B(P＜0.05). The incidence of adverse reaction of the group B was significantly higher than those of the group A, and the incidence of adverse reaction of the group C was significantly higher than those of the group A and the group B(P＜0.05).CONCLUSION Levofloxacin combined with high-dose ambroxol hydrochloride aerosol inhalation in the treatment of COPD to help control inflammatory response and improve clinical efficacy.