Objective To analyze the optimal threshold of Doppler ultrasonography(DUS)in the diagnosis of hepatic artery stenosis(HAS)after liver transplantation and propose the diagnostic criteria of CT angiography(CTA) or digital subtraction angiography(DSA)for patients with tardus parvus waveform(TPW)in combination with liver dysfunction. Methods Clinical data of 171 patients undergoing liver transplantation, postoperative conventional DUS, liver function test, CTA or DSA were collected. The optimal threshold of resistance index(RI)and systolic acceleration time (SAT)for the diagnosis of HAS were determined by multi-level likelihood ratio(MLR). Different diagnostic criteria were established and the diagnostic efficacy was statistical y compared. Positive TPW was defined as the diagnostic criterion with low confidence, positive TPW+liver dysfunction as the moderate confidences, and positive TPW+liver dysfunction or positive TPW+optimal threshold as the high confidence. Results MLR revealed that RI<0.4 and SAT>0.12 s were the optimal threshold for the diagnosis of HAS. The specificity of diagnostic criteria with moderate and high confidence was significantly higher compared with that of the low confidence(P<0.05). Moreover, the false-positive rate was significantly decreased(P<0.05). The sensitivity of diagnostic criterion with moderate confidence was significantly lower than those of low and high confidence(both P<0.05), whereas the sensitivity did not significantly differ between the diagnostic criteria with low and high confidence(P>0.05). Conclusions For patients with positive TPW detected by DUS after liver transplantation, the optimal threshold of diagnostic criteria combined with liver dysfunction contribute to appropriate clinical decision-making for clinicians.