Aim To investigate the anti-proliferating effect of tetrandrine ( Tet ) on colon cancer cells and its possible molecular mechanism. Methods We intro-duced crystal violet staining and flow cytometry to ana-lyze the effect of Tet on proliferation in LoVo cells. Flow cytometry was used to detect the effect of Tet on apoptosis in LoVo cells. Western blot assay was taken to analyze the effect of Tet on the expression of insulin-like growth factor binding protein 5 ( IGFBP5 ) . Final-ly, luciferase reporter assay, recombinant adenovirus mediated over-expression or silence of IGFBP5 were used to analyze the possible role of IGFBP5 in the anti-proliferating effect of Tet on colon cancer cells. Re-sults Crystal violet staining and flow cytometery anal-ysis results showed that Tet could exert an anti-prolifer-ating effect and induce apoptosis in LoVo cells. Tet de-creased the expression of IGFBP5 in a concentration-dependent manner. Tet inhibited the transcriptional ac-tivity of pTOP-luc reporter, which could be reversed by exogenous expression of IGFBP5 mostly. Similar results were found in the expression of c-Myc, but IGFPB5 knockdown couldn’ t reverse this effect. Conclusion Tet can inhibit the proliferation of colon cancer cells, and this effect may be mediated by down-regulating the expression of IGFBP5 to inhibit Wnt/β-catenin signa-ling transduction partly.