Objective: To explore the relationship between Helicobacter pylori (Hp) infection and atrial fibrillation (AF) in Chinese patients. Methods: A total of 285 hospitalized patients with AF and 300 patients from Health Screening Center who matched age and sex with AF group were enrolled. AF patients were divided into two groups: the short-standing AF category (less than a year) and the long-standing AF category (more than a year). All patients had laboratory testing of C-13 urea breath test, high-sensitive C-reactive protein (hs-CRP) and left atrial diameter (LAD). We analyzed the difference of these factors in all groups and explored the correlation between Hp infection and AF using logistic regression analysis. Results: Both AF groups had more hypertension, diabetes, and Hp infection than the control group. The Hp value and the hs-CRP level in patients with long-standing AF were higher than those in the short-standing AF and the control groups (for Hp value: P < 0.001 for both and for hs-CRP level: P=0.003, 0.002, respectively). The LAD of patients in the long-standing AF group was significantly larger than those in the short-standing AF group and control group (P=0.001 and P. 0.001, respectively). The values of Hp, hs-CRP, and LAD in the long-standing AF category were significantly higher than those in the short-standing AF category (all P < 0.05). After controlling the potential confounders, Hp value >= 4 parts per thousand, hs-CRP. 5 mg/L, and LAD >36 mm were significantly related to long-standing AF. Conclusion: The values of Hp in patients with long-standing AF were significantly higher than those in short-standing AF and control groups. Hp delta value >= 4 parts per thousand is an independent predictor for long-standing AF.