Background: Patients with atrial fibrillation (AF) underwent a high risk of hospitalization, which, however, has not been paid much attention in clinic. Therefore, we aimed to assess the incidence, causes and predictors of hospitalization in AF patients.Methods: From August 2011 to December 2017, 20,172 AF patients from the Chinese Atrial Fibrillation Registry (China-AF) Study were enrolled in this study. We described the incidence, causes of hospitalization according to age and gender categories. The Cox proportional hazards model was employed to identify predictors of first all-cause and first cause-specific hospitalization. Results: After a mean follow-up of 37.3 ± 20.4 months, 7,512 (37.2%) AF patients experienced one or more hospitalizations. The overall incidence of all-cause hospitalization was 24.0 per 100 patient-years. Patients aged < 65 years were predominantly hospitalized for AF (42.1% of the total frequency of hospitalizations); while patients aged 65-74 and ≥ 75 years were mainly hospitalized for non-cardiovascular diseases (43.6% and 49.3%, respectively). Multivariate Cox model analysis verified the higher risk of hospitalization in patients complicated with heart failure (HF)[hazard ratio (HR) 1.15, 95% confidence interval (CI) 1.08-1.24], established coronary artery disease (CAD) (HR 1.26, 95%CI 1.19-1.34), ischemic stroke/transient ischemic attack (TIA) (HR 1.26, 95%CI 1.18-1.33), diabetes (HR 1.16, 95%CI 1.10-1.22), chronic obstructive pulmonary disease (COPD) (HR 1.41, 95%CI 1.13-1.76), gastrointestinal disorder (HR 1.39, 95%CI 1.23-1.58), and renal dysfunction (HR 1.31, 95%CI 1.16-1.48). Conclusions: More than one-third of AF patients included in this study were hospitalized at least once during almost 3 years of follow-up. The main cause for hospitalization among elderly patients (≥65 years) is non-cardiovascular diseases rather than AF. Multidisciplinary management of comorbidities should be advocated as strategies to reduce hospitalization in AF patients.Clinical Trial Registration: URL: http://www.chictr.org.cn/showproj.aspx?proj=5831. Unique identifier: ChiCTR-OCH-13003729.