Abstract: Objective:To investigate the expression level of pyruvate kinase M 2 (PKM 2) in tissues of non-small cell lung cancer (NSCLC) patients and the correlation between PKM 2 expression level and radiation sensitivity. Methods:A total of45NSCLC pa-tients were chosen and treated with radiotherapy for two months after surgery. The patients were classified into four groups based on the curative effect. The mRNA expression levels of PKM 2 in tumor and the homologous paraneoplastic tissues of NSCLC patients were de-tected prior to radiotherapy using real time-polymerase chain reaction (RT-PCR), and the protein expressions of PKM 2 in the tumor and paraneoplastic tissues of NSCLC patients were detected with Western blot analysis and immunohistochemical method. The mRNA and protein expression levels of PKM 2 in the tumor tissues of different groups were detected with RT- PCR and Western blot assays. Re-sults: The effective rate of radiotherapy for 2 months is 44.8% in NSCLC patients. The expression level of PKM2 is significantly high-er in tumor tissues than in homologous paraneoplastic tissues of NSCLC patients and is negatively correlated with the curative effect of radiotherapy. Conclusion:The expression level of PKM2 is significantly higher in tumor tissues than in the paraneoplastic tissues of NSCLC patients. Patients with lower PKM2 expression level are more sensitive to radiotherapy.