Objective To evaluate the applicating value of transit time flow meter（TTFM） in determing the status of coronary grafting and analyze the correlation factors of the measuring results. Methods Three hundred and one patients underwent CAB（3 in this hospital from March 2002 to January 2004. Seven hundred and ninety-one grafts were measured with TTFM. One hundred and sixty-five patients whose left internal mammary artery （LIMA） were grafted to left anterior descending branch （LAD） were included in this retrospective study according to inclusion criteria, the graft flow and pulsatility index（P1） as dependent and the other 17 factors as independent factors which were analyzed by muhilinear regression analysis. Results According to TTFM technique, technical errors of 5 grafts had been detected and corrected intraoperatively among 791 grafts. The graft flow of LIMA-LAD related strictly to LAD distal diameter, LIMA diameter, anterior myocardial infraction, stenosis degree of proximal LAD, percentage of insufficiency （% insufficiency）, left ventricle end-diastole diameter and different surgical technique （on- pump, off-pump）. PI was influenced by LAD distal diameter, different surgical technique （on-pump, off-pump） and %insufficiency. Conclusions Evaluation of TTFM is valuable in determining the status of a coronary graft after CAB（3. Multiple factors could influence the grafts flow and the PI. The intraoperative technical control of anastomoses should be considered together with major influential factors and cardiac performances.