The purpose of this study is to evaluate the changes of lung function before and after the exercise in patients with chronic obstructive pulmonary disease.The assessment of quality of life is also carried out through questionnaires.

This is a randomized,open-label study to research the changes of lung function before and after exercise in patients with chronic obstructive pulmonary disease .At baseline,lung function test,blood oxygen saturation and pulse are measured before and after 6-min walk test for each subject.Quality of life is assessed through questionnaires including modified Medical Research Council dyspnoea scale(mMRC),St George's Respiratory Questionnaire(SGRQ),Clinical Chronic Obstructive Pulmonary Questionnaire(CCQ) and chronic obstructive pulmonary assessment test(CAT).And then budesonide(160ug) and formoterol(4.5ug) bid will be given to the subjects for 3 months.The subjects will have a follow-up visit with all the examinations mentioned above after 3 months' treatment.

Inclusion Criteria:

• Male or female patients 18 to 80 years-old, inclusive.
• A clinical diagnosis of chronic obstructive pulmonary disease according to the Global Initiative for Chronic Obstructive Disease(GOLD 2018) guidelines.
• Post bronchodilator (following inhalation of salbutamol) forced expired volume in one second(FEV1)/forced vital capacity(FVC) ratio ≤0.70.
• Willing and able to provide written informed consent.
• Willing and able to attend all study visits and adhere to all study assessments and procedures.

Exclusion Criteria:

• Severe comorbidities including unstable cardiac or pulmonary disease or any other medical conditions including unstable ischemic heart disease,unstable cardiac arrhythmia or heart failure,life threatening arrhythmias,etc.
• Recent history of chronic obstructive pulmonary disease exacerbation requiring hospitalization or need for increased treatments for chronic obstructive pulmonary disease within 6 weeks.