Objective:To investigate the expression level of pyruvate kinase M2 (PKM2) in tissues of non-small cell lung cancer (NSCLC) patients and the correlation between PKM2 expression level and radiation sensitivity. Methods:A total of 45 NSCLC 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 PKM2 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 PKM2 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 PKM2 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.