Objective: To analyze the predictive value of pregnancy outcome in freeze-thaw embryo transfer (Freeze-melt embryo transfer; FET). Methods: 80 infertility patients treated with FET from June 2019 to December 2021 were selected as the study subjects, Continue with luteal supportive therapy with positive human chorionic gonadotropin (β -HCG) on the 14th d after transplantation, On the 28d after transplantation, the pregnant group (47), Biochemical pregnancy and no pregnancy were included in the un pregnant group (33 cases), For all patients were diagnosed using color Doppler ultrasound, To compare the level of ultrasound diagnostic index between FET patients with different pregnancy outcomes [uterine artery blood flow resistance index (resistance index; RI), beat index (pulsatility index; PI), endometrial vascular blood flow index (flow index; FI), the endometrial vascular index (Vascular index; VI) and the vascular blood flow index (Vascular flow index; VFI)], deep classification of endometrial blood vessels, endometrial negative peristalsis wave changes, Building a Logistic regression prediction model, The predictive value of ultrasound test in the pregnancy outcome of FET was explored. Results: (1) the RI and PI levels were lower than the non-pregnant group, VFI and FI were higher than those in the non-pregnant group, Statistically significant differences between the groups (P <0.05), There was no significant difference in VI level between pregnant and non-pregnant groups (P> 0.05); (2) There was no significant difference in endometrial vascular depth classification between pregnant group and non-pregnant group (P> 0.05); (3) There was no significant difference in the negative peristalsis wave between the pregnant and the non-pregnant groups (P> 0.05); (4) The results of the Logistic regression analysis showed that, High levels of PI and RI, Both VFI and low FI levels were the influencing factors for the adverse pregnancy outcomes of FET (P <0.05); (5) Results of drawing the ROC curve for display: The best cut-off value of the prediction model was 0.0887, Area under the ROC curve (area under curve, AUC) was 0.710 (0.646~0.778), 0.715 (0.654~0.782), 0.724 (0.677~0.811), 0.702 (0.651~0.779) and 0.886 (0.798~0.989). Conclusion: Sonography has high predictive value in FET pregnancy outcome. In FET patients, PI and RI are expressed at high levels and VFI and FI at low levels, with high predictive value, which is recommended for clinical use.