Background Low-density lipoprotein cholesterol (LDL-C) reduction improves cardiovascular outcomes. This study investigates the relationship between lipid levels and outcomes in patients with nonvalvular atrial fibrillation by LDL-C quarters. Material/Methods Patients with atrial fibrillation were enrolled from 31 typical hospitals in China. Of 19 515 patients, 6775 with nonvalvular atrial fibrillation (NVAF) were followed for 5 years or until an event occurred. Results Hyperlipidemia was not an independent risk factor for stroke/thromboembolism and cardiovascular mortality among patients with NVAF (hazard ratio 0.82, 95% CI 0.7–0.96, P =0.82). When patients were divided into quartiles according to LDL-C levels at the time of enrollment (Q1, <1.95; Q2, 1.95–2.51; Q3, 2.52–3.09; and Q4, >3.09 mmol/L), as LDL-C increased, events tapered off according to Kaplan-Meier curves for patients who were without oral anticoagulants and off statins (non-OAC; log-rank=8.3494, P =0.0393) and for those with oral anticoagulants (OAC; log-rank=6.7668 P =0.0797). This relationship was stronger for patients who were without OAC treatment and off statins than for those with OAC treatment. The relationship was not significant in patients with or without OAC and on statins (log-rank=2.5080, P =0.4738). This relationship also existed in patients with CHA2DS2-VASc scores <2 (log-rank=5.893, P =0.1167). For those with CHA2DS2-VASc scores ≥2 (log-rank=6.6163, P =0.0852), the relationship was stronger. Conclusions In patients with NVAF using standard or no lipid-lowering medication, low plasma LDL-C levels were related to an increased risk of stroke/thromboembolism and cardiovascular mortality.