Objective: To investigate the diagnostic value of contrast-enhanced ultrasound (CEUS) combined with lemur tyrosine kinase 3 (LMTK3) in papillary thyroid carcinoma (PTC) and cervical lymph node metastasis. Methods: 92 patients with thyroid tumors confirmed by operation and pathology in our hospital From February 2019 to February 2022 were selected. All patients underwent thyroid CEUS examination and LMTK3 examination before operation. The patients were divided into benign group (42 cases) and PTC group (50 cases) according to the pathological results, The PTC group underwent neck lymph node dissection, the patients were divided into metastasis group (28 cases) and non metastasis group (22 cases) According to the presence or absence of neck lymph node metastasis. The levels of CEUS and LMTK3 were compared between benign group and PTC group, metastatic group and non metastatic group. The receiver operating characteristic (ROC) curve were drawn to evaluate the diagnostic value of various parameters for PTC and cervical lymph node metastasis. Results: The proportion of CEUS enhancement, low enhancement, non-uniform enhancement, perfusion defect, unclear boundary during enhancement, time to peak (TTP) and LMTK3 level were significantly higher In PTC group than in benign group, while the peak intensity (PI) were significantly lower than that in benign group, and the difference was statistically significant (P<0.05). The proportion of CEUS enhancement, high enhancement, non-uniform enhancement, perfusion defect, unclear boundary during enhancement, TTP, PI and LMTK3 levels in thyroid nodules were significantly higher in PTC cervical lymph node metastasis group than in non metastasis group, and the difference was statistically significant (P<0.05). Compared with CEUS and LMTK3 alone, the combined diagnosis of PTC and cervical lymph node metastasis has the highest accuracy, sensitivity and specificity. Conclusion: CEUS and lmtk3 have certain differential diagnostic value for PTC and cervical lymph node metastasis. The combined detection of CEUS and LMTK3 can help to improve the diagnostic accuracy of PTC and cervical lymph node metastasis before operation.