The purpose of study is to evaluate the efficacy and safety of Benzalkonium Chloride Solution clearing the oral colonized bacterium in hospitalized patients with COPD.

This a randomized, double-blind, parallel, single-center, exploratory trial. 60 patients will be randomized to two treatments: benzalkonium chloride solution treatment or normal saline treatment.The purpose of study is to evaluate the efficacy and safety of benzalkonium chloride solution clearing the oral colonized bacterium in hospitalized patients with COPD.

Inclusion Criteria:

1. COPD patients in hospitalized.
2. Aged from18 to 70 years (including 18 and 70).
3. Patients participating in this trial should sign ICFs.
4. Patients with good understanding, could conduct this study with investigators.

Exclusion Criteria:

1. History of mouthwash allergies, allergic rhinitis or dermatitis.
2. Patients with oral ulcers, severe periodontal disease, oral mucosal lesions or oral cancer, patients received special oral clean.
3. Patients with removable denture.
4. Patients with malignant blood diseases.
5. History of using cytotoxic drugs or biological immunosuppressants ( such as TNF-α inhibitors ).
6. Had used clinical study drugs before 28 days enrollment.
7. Had used clinical study drugs before 28 days enrollment.