Abstract: Objective 　To investigate effect of Ku80 on esophageal carcinoma cells and it s t ransplanted models in nude mice, inhibition of Ku80 expression by shRNA vector was used. Methods 　shRNA2Ku80 vector was const ructed, using RNA interference technology. The effectiveness and feasibility of RNA in2 terference were confirmed by Western blot and RT2PCR methods. Effect s of silencing Ku80 by shRNA on esophageal carcinoma cells and it s t ransplanted models in nude mice were investigated by MTT assay, Colony formation assay and inhibition of tumor assay in vi vo. Effect s of silencing Ku80 by shRNA on cell cycle and apoptosis were observed by Flow cytomet ry analysis. Results 　ShRNA2Ku80 vector was con2 st ructed successfully. Silencing Ku80 by shRNA inhibited esophageal cells growth in vi t ro and i n vi vo. Silencing Ku80 by shRNA made cell cycle arrest in G2 / M phase and enhanced apoptosis induced by radia2 tion. Conclusion 　Ku80 plays a role in occurrence and development of esophageal cancer, inhibition of Ku80 expression by shRNA may become a target of gene therapy of tumor.