The aim of this article is to study the regulatory feedback loop between β-catenin and IQ motif containing GTPase activating protein 1 (IQGAP1), as well as the effect of this regulation loop in colon cancer cell proliferation. Western blot was used to detect the expression of IQGAP1 and β-catenin after changing their expression respectively by transfection in SW1116 cells. CCK-8 cell proliferation assay was used to detect the effect of IQGAP1 involved in the proliferation of SW1116 cells promoted by β-catenin. The results of Western blot indicated that β-catenin could positively regulate IQGAP1, while IQGAP1 silencing could up-regulate β-catenin, forming a negative feedback loop. The results of CCK-8 showed that IQGAP1 silencing inhibited β-catenin-mediated proliferation in SW1116 cells. In conclusion, our research reveals a negative regulatory feedback loop between β-catenin and IQGAP1 which has a remarkable effect on the proliferation ability of colon cancer cells.