Transit time flow measurement (TTFM),which is independent of vessel size and shape, has been considered to be an easy, reproducible and non-invasive method to assess the hemodynamic characteristics. Moreover, current studies have shown that TTFM has clinical application in identifying the function of grafted vessel and prognosis. Researchers have proved some reliable indicators for the function of grafted vessel as follows: mean graft flow (MGF) > 15 ml/min, diastolic flow (DF) >50% and pulsatility index (PI)<3 or 5. This article focuses on the review of clinical application and research progress of TTFM in CABG.