Atrial fibrillation is one of the most common arrhythmias, which can cause embolism, heart failure, cardiac arrest, and other cardiovascular deaths, causing a serious economic burden on patients. Scholars have begun to explore the relationship between atrial fibrillation and hypothyroidism, including clinical hypothyroidism, subclinical hypothyroidism, and threshold state of thyroid function, which means that thyroid stimulating hormone, free triiodothyronine, and free thyroxine are high or low in the normal range. This article reviews the occurrence and mechanism of hypothyroidism promoting atrial fibrillation, and aims to provide a basis for clinical intervention in patients with hypothyroidism to reduce the occurrence of atrial fibrillation.