Abstract: Objective To investigate the effects and mechanism of knock-down the expression of mammalian target of rapamycin (mTOR) gene with RNA interference (RNAi) technique on growth and mechanism of colon cancer LoVo cell. Methods There were three groups in the study.Group 1 (normal group) was the normal cultured LoVo cells.Group 2 (positive experimental group) was the LoVo cells transfected with mTOR-RNAi plasmid vector.Group 3 (negative control group) was the LoVo cells transfected empty plasmid vector as negative control.Cell growth was assessed using MTT assay and tumor colony formation was detected.Cell cycle and apoptotic rate wereanalyzed via flow cytometry.Furthermore,the contents of adenosine triphosphate (ATP) in LoVo cells were measured by high performance liquid chromatography (HPLC). Results The rates of cell proliferation in the positive experimental group were slower than those in the normal cultured group.The colon formations of LoVo cells in the normal cultured group,the positive experimental group and the negative control group were (26.8±4.9)%,(11.8±2.1)% and (21.3±4.7)% respectively.Compared with those in the normal cultured group,the colon formations of LoVo cells in the positive experimental group were decreased significantly,and the ratios of cells in G₁ phase were increased by 8.6% and that in S phase were decreased by 8.0% and those in apoptosis were increased by 7.0% (all,P<0.01). The ATP contents in the normal cultured group,the positive experimental group and the negative control group were （2.47±0.20）nmol/106, （1.62±0.18）nmol/106 and （2.37±0.21）nmol/106 respectively. The ATP contents in the positive experimental group were lower than those in the normal cultured group (P<0.01). Conclusion Our results suggested that selective knock-down of mTOR could suppress LoVo cell proliferation by cutting down energy metabolism and inducing cell apoptosis.