In order to investigate the anti-tumor effect of RNA interference silencing HIF-1α and survivin genes combined with X-rays irradiation on human hepatoma xenograft in nude mice, siRNA expression plasmids targeting HIF-1α and/or survivin genes packed by liposome were injected into human hepatoma xenograft which were irradiated with 5 Gy X-rays later. Tumor volumes and mean survival period of mice at different time points were observed. Expression level of HIF-1α, survivin, PCNA and intratumoral microvessel density was detected by Immunohisto-chemical staining respectively. Apoptotic cells in tumor tissue were detected by TUNEL method. The results showed that tumor volumes of pGenesil-survivin-HIF+5 Gy group were significantly lower than that of pGenesil-survivin+5 Gy group and pGenesil-HIF+5 Gy group on the 9th—21th day after the beginning of therapy. Mean survival period of mice in pGenesil-survivin-HIF+5 Gy group was the longest. Expression level of HIF-1α, survivin, PCNA and intratumoral microvessel density in pGenesil-survivin-HIF+5 Gy group were significantly lower than that of the control group and the radiotherapy group on the 1st day after therapy. Percentage of apoptotic cells in tumor tissue in pGenesil- survivin-HIF+5 Gy group was significantly higher than that in the other groups. These results suggested that RNA interference silencing HIF-1α and survivin genes combined with radiotherapy could effectively inhibit cell proliferation and tumor angiogenesis and enhance apoptosis in tumor xenograft. Its anti-tumor effect was more powerful than that of radiotherapy, RNA interference silencing HIF-1α or survivin gene combined with radiotherapy respectively.