Chronic obstructive pulmonary disease (COPD) is heterogeneous and its presentation varies between countries. The major COPD cohort studies have only been performed in Western populations, the disease is not well characterized in other regions. The COMPASS (Investigation of the Clinical, Radiological and Biological factors, humanistic and healthcare utilization burden associated with disease Progression, phenotypes and endotypes of COPD in China; NCT04853225) is a prospective, 2.5 years, multi-center, longitudinal, observational study with three aims: 1) characterize stable and exacerbation phenotypes/endotypes in terms of clinical characteristics, blood and sputum biomarkers, lung microbiome and lung imaging; 2) understand the relevance of markers of COPD disease progression identified in Western cohorts to Chinese patients; 3) characterize treatment pathways and healthcare resource utilization. COMPASS will recruit 2000 participants, of which 1700 will be in GOLD grades I-IV (n=700, 700, 200, and 100, respectively), 180 participants with chronic bronchitis without airflow limitation, and 120 never-smoker healthy controls. Study visits will be at baseline, 6, 18 and 30 months and at exacerbation. Assessments include lung function, exacerbation frequency, health status, blood biomarkers and, in a sub-cohort of 400 patients, chest high-resolution computed tomography, additional blood and sputum biomarkers, airway micro-, viral- and myco-biome and physical activity. COMPASS will establish a unique clinical and biological dataset in a well-characterized cohort of individuals with COPD in China, with a particular focus on milder patients. As the first disease understanding study of its kind in an Asian setting it will provide valuable insights into regional and ethnic differences in COPD.