[Objective]To study the apoptosis of CT26 cells of mouse colon cancer induced by the vombination of arsenic trioxide(As2O3)and paclitaxel(PTX) and to research its mechanism. [Methods]CT26 cells of mouse colon cancer were treated by different concentrations of As2O3 for 72 h. Cell proliferation rate was detected by MTT method. Then,As2O3 having 30% inhibitory concentration was selected to carry out research together with different concentrations of PTX; cell proliferation rate was detected by MTT method. The dosage group having the most significant inhibitory effects was selected for the further research. Finally,apoptosis rate and cell cycle of each group were assessed by flow cytometer. [Results]Different concentrations of As2O3 or PTX significantly inhibited CT26 cell proliferation in a dose dependent manner.Combination of 2. 0 μmol /L As2O3 and 0. 04 μmol /L PTX had synergistic inhibition effects on CT26 cell proliferation,and showed more significant effects on enhancing the apoptosis rate of cells.[Conclusions] Combination treatment of As2O3 and PTX inhibited cell growth and induced apoptosis. [Objective] To study the apoptosis of CT26 cells of mouse colon cancer induced by the vombination of arsenic trioxide (As2O3) and paclitaxel (PTX) and to research its mechanism. [Methods] CT26 cells of mouse colon cancer were treated by different concentrations of As2O3 having 30% inhibitory concentration was selected to carry out research together with different concentrations of PTX; cell proliferation rate was detected by MTT method. The dosage group having the most significant inhibitory effects was selected for the further research. Finally. apoptosis rate and cell cycle of each group were assessed by flow cytometer. [Results] Different concentrations of As2O3 or PTX significantly inhibited CT26 cell proliferation in a dose-dependent manner. 0 μmol / L As 2 O 3 and 0. 04 μmol / L PTX had synergistic inhibition effects on CT26 cell proliferation, and showed more significant effects on apoptosis osis rate of cells. [Conclusions] Combination treatment of As2O3 and PTX inhibited cell growth and induced apoptosis.