Atrial fibrillation is one of the most common arrhythmias, causing a significant medical burden worldwide. A large number of studies have shown that the inflammatory response plays a vital role in the occurrence, maintenance and progression of atrial fibrillation. Therefore, it is particularly important to find a simple and accessible inflammatory marker as a tool to assess the severity and prognosis of atrial fibrillation. Neutrophil/lymphocyte (N/L) ratio, a cheap, simple and accessible marker of inflammation, has attracted much attention in recent years. At present, many research evidences show that N/L is closely related to the occurrence and development of atrial fibrillation. This article summarizes the existing evidence and finds that N/L has important clinical value in predicting the occurrence, treatment efficacy, recurrence, and complications of atrial fibrillation.