[Abstract]: Objective: To explore the correlation between contrast-enhanced ultrasound and ultrasound elastography in the evaluation of thyroid cancer and cervical lymph node metastasis in the context of Hashimoto thyroiditis (HT). Methods: 137 patients with thyroid lesions under HT background were collected from January 2021 to March 2022. All patients underwent ultrasonic elastography and contrast-enhanced ultrasonography. The diagnostic efficacy of ultrasonic elastography and contrast-enhanced ultrasonography was analyzed by ROC curve. At the same time, according to whether thyroid cancer patients have cervical lymph node metastasis under the background of HT, they are divided into two groups, namely metastasis group (n = 41) and non metastasis group (n = 38). The quantitative parameters of ultrasound in the two groups are compared, and the correlation between quantitative parameters of ultrasound and cervical lymph node metastasis of thyroid cancer is analyzed. Results: the accuracy of contrast-enhanced ultrasound in the diagnosis of thyroid lesions under HT background was 84.67%, the accuracy of ultrasound elastography was 72.99%, and the accuracy of two combined diagnosis was 94.16%. The AUC of ultrasound elastography, contrast-enhanced ultrasound and two combined diagnosis of thyroid cancer under HT background were 0.727, 0.844 and 0.940 respectively. Time To Peak (14.32 ± 4.58) s and Mean Transit Time (28.46 ± 8.42) s in patients with metastasis were lower than those in patients without metastasis, and the elastic ratio (2.51 ± 0.51) was higher than that in patients without metastasis (P < 0.05). By Spearman method, TTP and MTT were negatively correlated with cervical lymph node metastasis and positively correlated with elastic ratio; By ROC curve analysis, the AUC of TTP, MTT, elastic ratio and three combined early diagnosis of cervical lymph node metastasis of thyroid cancer under the background of HT were 0.788, 0.772, 0.767 and 0.948 respectively. Conclusion: ultrasound elastography combined with contrast-enhanced ultrasound is highly effective in the diagnosis of thyroid cancer and cervical lymph node metastasis under the background of HT, and has a certain guiding value for clinical practice. [Key words]: contrast-enhanced ultrasound; Ultrasonic elastography; Hashimoto thyroiditis; Thyroid cancer; Cervical lymph node metastasis; relevant