Abstract: Objective To investigate the in vitro effect of DNA methyltransferase inhibitor SGI-1027 on proliferation，apoptosis and cell cycle of colon cancer LoVo cells, as well as the possible mechanism. Methods The LoVo cells in the logarithmic growth phase were used in this study，and the LoVo cells exposured to SGI-1027 with final concentrations of 0.1，1，5 and 10 μmol／L were chosen as experimental group. Inverted phase contrast microscope was used to observe morphology of LoVo cells. The cells in control group were synchronously cultured in RPMI 1640 with 10％ fetal bovine serum. The proliferation inhibition rates of SGI-1027 on LoVo cells were detected by adding MTT solution after 24，48 and 72 h. After SGI-1027 treatment，1×106 cells per concentration were harvested for the detection of cell apoptosis rate and cell cycle phase distribution by flow cytometry with Annexin-V fluorescein isothiocyanate（FITC）／propidium iodide（PI）double staining and PI staining，respectively. The effect of SGI-1027 on PI3K／Akt pathway was evaluated by Western blotting. Results Inverted phase contrast microscope showed that the morphological chages of LoVo cells were more obvious treated by SGI-1027 in dose and time dependent manner. In addition to the treatment with 0.1 μmol／L SGI-1027 for 24 h，the proliferation inhibitory rates were increased in time and dose dependent manner. Compared with control group，the apoptotic rates of LoVo cells treated by SGI-1027（0.1-10 μmol／L）at 24, 48 h were all increased， and the differences between different concentrations were statistically significant（P＜0.05）. Compared with control group，the proportion of G0／G1 phase and the level of PTEN increased after SGI-1027 treatment（1-10 μmol／L）,but the proportions of both S phase and G2／M phase cells as well as the level of Akt decreased（P＜0.05）. Conclusion SGI-1027 could inhibit the proliferation of LoVo cells and induce apoptosis and G0／G1 arrest，and the time and concentration of SGI-1027 treatment have effect on the malignant behavior of LoVo cells.