The role of CyclinB1 in conferring drug resistance in the treatment of liver cancer was investigated. siRNA delivery was used to knockdown the expression of CyclinB1, and flow cytometry analysis was employed to assess cell apoptosis and cell cycle distribution .Colony formation assay and cytotoxicity assay were used to determine cell growth ability. It was found that siRNA induced CyclinB1 down regulation triggered cell arrest at G2/M by 40%～50% and greatly inhibited cell colony growth ability. Daunorubicin in combination with CyclinB1 siRNA induced more apoptosis than that treated with Daunorubicin alone, whereas this combinational effect decreased in HL-7702 cells, a normal human liver cancer cell line. Those data support the notion that targeting CyclinB1 down regulation combined with chemotherapeutical agents would be a promising new strategy in the treatment of liver cancer.