Objective:To compare the ability to resist exogenous reactive oxygen species（ROS）between Huh7 and SMMC-7721 cell lines and to explore the ROS resistance mechanisms in hepatocellular carcinoma（HCC）cell lines preliminary. Methods:After hepatoma cell lines Huh7 and SMMC-7721 being treated with different concentrations of H

2

O

2

differences in cell apoptosis and necrosis were compared

contents and cell activity of ROS

superoxide dismutase（SOD）

reduced glutathione（GSH）were measured

changes in expression of CSCs molecules

ROS scavenger enzyme genes

DNA repair gene between the two cell lines were detected. Results:After being treated with the same concentration of H

2

O

2

cell line SMMC-7721 had more apoptosis and necrosis and lower cell activity than cell line Huh7;the dead cells of SMMC-7721 and Huh7 in total of 1

500 cells were（841.7±78.7）

（169.7±76.1）（t=10.638

P=0.000）and cell activities were（0.21±0.02）

（0.74±0.14）（t=6.478

P=0.022）when H

2

O

2

concentration was 1 μmol/m L;the content of ROS in hepatoma cells increased with the increase of concentration of H

2

O

2

but Huh7 had less change than that in SMMC-7721;ROS of SMMC-7721 and Huh7 were（128793±1 158）;（103 455±1 665）（t=21.639

P=0.000） at the level of 1 μmol/m L H

2

O

2

;Huh7

compared with cell line SMMC-7721

had higher levels of GSH

SOD and more slowly ROS increasing tendency and decreasing tendency of GSH and SOD after being exposed to different concentrations of H

2

O

2

;GSH of SMMC-7721 and Huh7 were（32.85±4.47）mg/g prot

（106.60±6.83）mg/g prot（t=15.655

P=0.000）and SOD were（19.22±2.93）U/mg prot

（23.57±4.85）U/mg prot（t=1.332

P=0.254）;the changes of the intracellular GSH and SOD changed earlier than that of ROS in liver cancer cells as a whole;ROS scavenging enzyme genes and DNA repair genes expressed in Huh7 cells was relatively higher than that in SMMC-7721 cells. Compared with cell line SMMC-7721

cancer stem cells（CSCs）molecules CD133

bmi-1

ROS scavenger enzyme gene SOD2 and DNA repair gene Rad51 were expressed higher in Huh7 than that in SMMC-7721. Conclusion:Cell line Huh7 had stronger ROS resistance ability than cell line SMMC-7721 and higher expression of CD133

Bmi-1

SOD2 and Rad51. Those genes may be involved in the process of liver cancer cells’ ROS resistance through regulating intracellular GSH and SOD.