【Objective】 To investigate the clinical value of liquid-based cytological test (LCT) and transbronchial needle aspiration (TBNA) in the diagnosis of mediastinal lymph node metastasis in non-small cell lung cancer. 【Methods】 The clinical data of 96 patients with lung cancer diagnosed by conventional electronic bronchoscopy from August 2011 to December 2013 in our hospital were retrospectively analyzed. Mediastinal staging by TBNA was performed before operation. TBNA specimens were prepared by conventional smears (CS) and liquid-based cytological test (LCT) smears respectively. All patients subsequently underwent pulmonary resection with mediastinal lymph node dissection. The differences in the cytopathological diagnosis between the two preparation methods of TBNA specimens were compared. The diagnostic sensitivity, specificity, accuracy, positive predictive value and negative predictive value were evaluated. 【Results】 96 patients with 258 lymph nodes were punctured. TBNA procedures were successfully carried out in 519/539 (96.29%). The positive rate of TBNA specimens by LCTwas 84.88% (219/258), while the positive rate of TBNA specimens by CS was 54.65% (141/258), the difference was statistically significant (P <0.01). No complications happened in the group. Overall diagnostic sensitivity, specificity, accuracy, positive predictive value and negative predictive value of cytopathology for mediastinal lymph node metastasis by TBNA of LCT smears were 96.05%,100%,96.51%,100% and 76.92%, while those of CS smears were 61.84%,100%,66.28%,100% and 25.64%. The area under the ROC curve of CS method was 0.547, while that of LCT method was 0.867. The sensitivity, negative predictive value and accuracy of LCT smears were higher than those of CS, the difference was statistically significant (P <0.01). 【Conclusion】 The combined method of LCT and TBNA is a safe and effective technique in diagnosing mediastinal lymph node metastasis of NSCLC, which has certain clinical application value.