Abstract: Objective : This experiment used galactose (Gal)-polyethyleneimine (PEI) as a vector,delivered c-m yc antisense oligodeoxynucleotides (ASODN) to human hepatocellular carcinoma Bel-7402 cells in order to investigate if Gal -PEI -ASODN complex can enhance drug sensitivity on Bel-7402 cell lines with arsenic trioxide (Arsenic Trioxide, As₂O₃), 5 -fluorouracil (5 - FU) and Pharmorbincin (PHA). Methods : Bel-7402 cells incubated with different concentrations of As₂O₃, 5-FU,PHA alone or combining with c-myc ASODN or Gal-PEI-ASODN. The inhibitory rate of cell proliferation was tested using a cell counting kit (WST - 8 method) and the IC 50 was calculated. Results : Different chemotherapeutic drugs (As₂O₃; 5-FU, PHA) combined with Gal -PEI - ASODN (0.25μmol/L) reduced the IC 50 on Bel-7402 cells and chemotherapeutic drug's sensitivity was enhanced 3.58, 1.58 and 2.05 times comparing with pure chemotherapeutic drug group respectively. Conclusions : Gal -PEI-A -SODN can enhance chemotherapeutic drug's sensitivity on Bel - 7402 cells of As₂O₃, 5 -FU, PHA. The best combined effect is tested in As₂O₃ combining with Gal-PEI-ASODN group.