Abstract: To observe and discuss the inhibition of the silencing of the nucleostemin ( NS ) gene in EC9706 cells, induced by RNAi on the growth of xenograft tumors in nude mice. Methods: Up to 15 BALB/c nude mice were divided into 3 groups ( EC9706 cells transfected with pRNAT-U6.1-siNS2; EC9706 cells transfected with pRNAT-U6.1-siC; and normal EC9706 cells ) with 5 mice in each group. The pRNAT-U6.1-siNS2-transfected EC9706 cells, the pRNAT-U6.1-siC-transfected EC9706 cells, and the normal EC9706 cells were hypodermically infused with siRNA intervention ( Group A ), the control without siRNA intervention ( Group B ), and the blank ( Group C ), respectively. The size of the xenograft tumors was measured in the mice after 5 weeks of inoculation. The NS gene mRNA expression in the tumors of the nude mice was detected using reverse transcriptase polymerase chain reaction. Results: Macroscopic tumors were observed in the injected position in Groups B and C at 4 days after the inoculation, and in Group A at 6 days after the inoculation. In the 5th week after inoculation, the percentage of tumorigenesis was 100% in the nude mice in every group. The size of the tumors was ( 847.00 ± 82.25 ) mm3, ( 1702.20 ± 88.60 ) mm3, and ( 1806.40 ± 77.75 ) mm3 in Groups C, B, and A, respectively. There were statistical differences among the three groups ( P < 0.05 ). The NS gene mRNA expression of the tumors were 0.681 ± 0.033, 0.685 ± 0.034, and 0.497 ± 0.056 in Groups C, B, and A, respectively. There were statistically significant differences among the three groups ( P < 0.05 ). Conclusion: Silencing the NS gene in EC9706 cells inhibits the growth of xenograft tumors in nude mice and decrease NS gene expression. Silencing NS gene is a promising new strategy for treating esophageal cancer.