Background: Several factors determine the efficacy of warfarin anticoagulation in patients with non-valvular atrial fibrillation (NVAF). This study aimed to use data from the Chinese Atrial Fibrillation Registry study to assess the control of anticoagulation therapy in Chinese patients with NVAF treated with warfarin. Material/Methods: From the Chinese Atrial Fibrillation Registry study the anticoagulant use and dosing, the time in therapeutic range (TTR) of the international normalized ratio (INR), and standard deviation of the observed INR values (SDINR), and their influencing factors were evaluated. Results: The median INR and SDINR were 2.04 (IQR 1.71-2.41) and 0.50 (IQR, 0.35-0.69), respectively. The median TTR was 51.7% (IQR, 30.6-70.1%) and only 25.1% had a TTR >= 70%. Age was >= 70 years (OR, 0.72; 95% CI, 0.55-0.94; P=0.015), bleeding history (OR 0.48; 95% CI, 0.23-0.89; P=0.029), the use of a single drug (OR, 0.62; 95% CI, 0.42-0.92; P=0.016), more than drug (OR, 0.60; 95% CI, 0.41-0.88; P=0.009), and lack of assessment of bleeding risk (OR, 0.72; 95% CI, 0.54-0.97; P=0.033) were associated with TTR <70% (INR 2.0-3.0). Coronary heart disease (CHD) and peripheral artery disease (PAD) (OR, 0.69; 95% CI, 0.52-0.90; P=0.007) and diabetes mellitus (OR, 0.79; 95% CI, 0.62-0.99; P=0.044) were associated with increased variability in INR (SDINR >= 0.5). Conclusions: In Chinese patients with NVAF, warfarin anticoagulation was associated with lower TTR and less stable anticoagulation than in current guidelines, and risk factors for reduced safety and efficacy were identified.