This is a 5-year multi-center observational prospective longitudinal cohort study to to establish the large COPD cohort and biological database in China, including COPD subjects( n= 3000) and GOLD 0 subjects (n= 800).Sites Investigators will be respiratory physicians working in the respiratory department of our sites, which must be tier 2 or tier 3 hospitals in China, with the equipment and ability to conduct pulmonary function test, HRCT.Patients must meet all the inclusion criteria and none of the exclusion criteria.No additional investigational drugs will be applied to the patients. Full analysis set will be used for all analyses. Missing data will be analysed as it is. Statistical analysis will be conducted by epidemiology \& statistics work group from Chinese Academy of Sciences, using SAS and SUDAAN software. An electronic data capture system will be used in this study. Paper-based questionnaire administration will also be used.Questionnaire variables will be checked before data entry.During the study, PI will be in charge of the monitoring of the whole procedure. Two working group will do the data cleaning and data analysing.
