Objective To investigate the expression and clinical significance of Notch-1 protein in papillary thyroid carcinoma (PTC) tissues and cervical lymph node metastases. Methods Immunohistochemical method was used to detect the expression of Notch-1 protein in 69 cases of PTC tissues, along with tumor adjacent tissues and 34 cases of metastatic lymph node tissues, and to analyze its role in PTC and metastatic lymph node tissue. Results Compared with PTC tissues or cervical lymph node metastases and tumor adjacent tissues, the positive rates of expression of Notch-1 protein in PTC tissues or cervical lymph node metastases were significantly lower than that in cancer adjacent tissues (P＜0.05). The expression of Notch-1 protein was correlated with the tumor size and capsule invasion of patients with PTC. Conclusions Notch-1 protein expression is decreased in PTC tissues and metastatic lymph node tissues, suggesting that the Notch-1 protein may play an important role in the development, invasion and metastasis of PTC. There is no significant difference in the positive rates of Notch-1 protein expression in PTC tissues and metastatic lymph node tissues, it's suggested that the malignant degree of cancer cells in lymph node metastasis is not significantly increased, and the biological behavior remained relatively stable.