To evaluate the efficacy of TQC3721 Suspension for Inhalation in patients with moderate to severe Chronic obstructive pulmonary disease (COPD)

Inclusion Criteria:

1. Sign an informed consent form before screening and fully understand the trial content, process, and potential adverse reactions.
2. Comply with the experimental schedule and be able to use the nebulizer inhaler correctly.
3. The age range is 40 to 80 years old (including the threshold), and both male and female participants are eligible.
4. The subjects have no pregnancy plans and voluntarily take effective contraceptive measures for at least one month from screening to the last use of the study drug.
5. Patients with a clear clinical history and related symptoms of COPD before screening.
6. Capable of conducting acceptable and reproducible lung function tests.
7. COPD clinical stability (no moderate to severe COPD acute exacerbation) within the 4 weeks prior to screening visit (V1 visit) and between V1 visit and V2 visit.
8. Smoking history ≥ 10 pack years.

Exclusion Criteria:

1. A history of life-threatening COPD, including admission to the intensive care unit and/or the need for intubation.
2. COPD acute exacerbations requiring systemic hormone therapy within 3 months prior to screening visit (V1 visit) or prior to randomization visit (V2 visit).
3. Within the first 6 months of screening, there has been at least 1 hospitalization history due to acute exacerbation of COPD or pneumonia.
4. Treatment with antibiotics for upper and/or lower respiratory tract infections within 6 weeks prior to screening or randomization visit (V3 visit).
5. Simultaneously suffering from other respiratory diseases.
6. Chest computed tomography (CT) revealed clinically significant abnormalities and concluded that the abnormalities were not caused by COPD.
7. Previous lung resection or lung reduction surgery.

11.Previously received TQC3721 treatment. 12.Patients who received immunosuppressant therapy within 4 weeks prior to the screening period 13.In the investigator's assessment, patients are unable to discontinue the prohibited drugs specified in the protocol during the screening and treatment phases of the study; 14.Patients with a history of uncontrolled current diseases that the investigator judges to be clinically significant; 15.A history or current evidence of clinically significant cardiovascular or cerebrovascular diseases; 16.A history of malignant tumors (cured or uncured) in any organ or system within the past 5 years; 17.Intolerance or allergy to salbutamol or other inhaled bronchodilator therapies for COPD; 18.Patients requiring long-term oxygen therapy; 19.Female subjects who are currently pregnant, breastfeeding, or planning to become pregnant during the study period after enrollment; 20.Having participated in any clinical trial of drugs or medical devices within 4 weeks or 5 half-lives (whichever is longer) prior to the screening visit; 21.Other conditions deemed unsuitable for participation in the study by the investigator.