Abstract: Objectives To explore the effects of VEGFsiRNA on chemosensitivity of leukemia cells to Ara-C. Methods VEGFsiRNA was constructed in vitro and then was transferred to HL60 cells. The proliferation was detected by CCK8 method. The level of VEGFmRNA was detected by reverse transcription and quantitative polymerase chain reaction (RT-PCR). The expression level of VEGF protein was determined by ELISA in cell culture medium. The cell apoptosis was detected by flow cytometry. Results VEGFsiRNA could increase the sensitivity of leukemia cells to Ara-C, and VEGFsiRNA combined with Ara-C significantly inhibited the survival of HL60 cells in which the inhibition rate was 82.9 percentages (F=121.63, P<0.01). VEGFsiRNA decreased significantly expression of VEGFmRNA121(F=17.17, P<0.01) and VEGF protein (F=3290.49, P<0.01). However, VEGFsiRNA didn’t promote the level of apoptosis induced by Ara-C. Conclusion VEGFsiRNA increases the sensitivity of leukemia cells to Ara-C by inhibiting proliferation.