Atrial fibrillation (AF) is a common complication after operation of lung cancer. Atrial fibrillation is often associated with longer hospital stay time and higher hospital cost, as well as increased postoperative mortality. The aim of this study is to explore the risk factors of atrial fibrillation (AF) in early period after operation of lung cancer and analyze its impact on short-term mortality, hospital stay time and hospitalization cost. From January 2006 to December 2007, 416 consecutive lung cancer patients underwent operation in our hospital were chosen. Postoperative ECG (electrocardiography) was used to diagnose AF. The cases were divided into two groups: AF group and control group (Non-AF group). Statistic Chi-Square test was used to compare numeration data and Logistic regression was performed to find risk factors of postoperative AF. In the 416 lung cancer patients, 52 cases (12.5%) were with AF and most occurred in the 1 to 3 days after operation. Multivariate analysis showed that the patients with age older than 65, preoperative pulmonary infection, low preoperative FEV1%pre, Intrapericardia operation and postoperative hypoxemia are prone to occur AF after operation. In AF group, the hospital stay time was longer, the hospitalization cost was higher. No obvious difference was observed with short-term mortality between the two groups. The incidence of AF after operation with lung cancer is 12.5% (52/416). Patients with age older than 65, preoperative pulmonary infection, low FEV1%pre, intrapericardia operation and postoperative hypoxemia have a higher risk of AF following operation. Although postoperative AF has no obvious impact on short-term mortality, it is associated with longer impatient time and higher hospitalization cost.