Objective To explore correlation of cardiac output (CO) and cardiac index (CI) measured by noninvasive cardiac output monitoring (NICOM) and thermodilution (Swan Ganz catheter), and to assess clinical value of NICOM. Methods Thirty-six adult patients undergone off pump coronary artery bypass surgery were selected. CO and CI parameters were measured by NICOM and Swan Ganz catheter simultaneously at nine time points: before incision (T1), opening chest （T2）, requiring internal mammary artery （T3）, opening pericardia （T4）, left anterior descending coronary artery bypass graft （T5）, diagonal branches （T6）, posterior descending branch （T7）, closing pericardial （T8）, and closing chest （T9）. The correlation of CO and CI parameters were evaluated. Results At T1, T3, T4  time points, the coefficient curve was fit in 0.858, 0.850, and 0.877 of CO, 0.752, 0.819, and 0.804 of CI, respectively （P<0.05）. Conclusion NICOM may provide accuracy references in perioperative period, which has complete correlation to Swan Ganz catheter.