To summarize the cases of clinical stage I non-small cell lung cancer (NSCLC) patients and analyze the risk factors of intrapulmonary (N.) lymph node metastasis in order to improve the accuracy of preoperative N staging and guide the development of surgical approach and treatment strategy. Methods The clinical data of 612 NSCLC patients treated surgically from September 2006 to December 2013 were retrospectively analyzed. Independent risk factors for the development of intrapulmonary lymph node metastasis in clinical stage I NSCLC were screened by univariate and multifactorial analyses. The results were 59 cases (9.6%, 59/612) with postoperative pathology of pN. Univariate analysis showed that male, smoking history, tumor diameter, tumor location (central type), pathological type (non-adenocarcinoma), degree of tumor differentiation and microinfiltration in the peripheral tumor vasculature were risk factors for the development of N, metastasis in patients with clinical stage I NSCLC. Multifactorial analysis showed that tumor diameter (OR=1.903, p<0.01), degree of tumor differentiation (OR=2.591, p<0.01) and vascular infiltration (OR=6.170, p<0.01) were independent risk factors for the development of n, metastasis in patients with clinical stage I nscLC. A roc curve analysis of tumor diameter yielded a N. metastasis rate of 15.O% at 2 2="">2 cm (p=0. 003). Conclusion The rate of intrapulmonary lymph node metastasis (pN,) in patients with clinical stage I NSCLC was 9.6%. Tumor diameter, degree of tumor differentiation and vascular infiltration were independent risk factors for intrapulmonary lymph node metastasis (pN.) in clinical stage I NSCLC. Patients with clinical stage I NSCLC >2 cm in diameter should be considered for preoperative invasive examinations such as PET-CT or EBUS-TBNA to clarify N stage.