ObjectiveTo investigate the risk factors of cervical lymph node metastasis of papillary thyroid microcarcinoma (PTMC) with clinical lymph node metastasis negative (cN0).MethodThe clinicopathologic data of patients with cN0 PTMC who underwent at least one lobectomy plus central lymph node dissection in this hospital from January 2013 to December 2018 were retrospectively collected and the risk factors of lymph node metastasis were analyzed.ResultsA total of 1 821 patients with cN0 PTMC were enrolled in this study. The results of postoperative pathology showed there were 837 (46.0%) cases with lymph node metastasis, in which of 805 (44.2%) cases with central lymph node metastasis; 252 (33.1%) had lateral lymph node metastasis among 761 patients underwent lateral lymph node dissection. The results of univariate analysis showed that male, age <55 years old, tumor diameter ≥5 mm, bilateral cancer, capsule invasion, and multiple foci were associated with lymph node metastasis of cN0 PTMC (P<0.05). Further binary logistic regression multivariate analysis results showed that these factors (except multiple foci) were the independent risk factors of lymph node metastasis of cN0 PTMC (P<0.05). While the results found that the risk of lateral lymph node metastasis was increased with the increasing of the number of central lymph node metastasis in patients with cN0 PTMC (P<0.05).ConclusionsCervical lymph node metastasis of cN0 PTMC is related to many factors, and central lymph node metastasis indicates a higher risk of lateral lymph node metastasis. For patients with risk factors, preventive central lymph node dissection should be given at the first surgery and decided whether to perform lateral lymph node dissection according to the intraoperative situation.