Abstract: ob＜x＞jective To investigate the effect and relate d mechanism of KIF4A on cell proliferation and cell cycle of colorectal cancer cells. Methods The KIF4A-CtrlRNA ( si-Ctrl) and KIF4A-siRNA ( si-KIF4A) were transiently transfect ed into colorectal cancer cell lines SW480 and DLD1, Western b lot was used to verified the effect of knocking down; the changes of cell p roliferation of SW480 and DLD1 colorectal cells were confirmed by CCK8 assay; flow cytometry was performed to analyze the effect of KIF4A on cell cycle; the changes of cell cycle-related proteins Cyclin D1, Cyclin E2 and CDK2 were performed by Western blot. Results Comparing the si-KIF4A group with si-Ctrl group, the ex＜x＞pression of KIF4A was significantly reduced; the cell proliferation was dramatically decreased; the cell cycle was arrested at G0/G1 phase and the cell cycle-related proteins Cyclin D1, Cyclin E2 and CDK2 were downregulated. Conclusion KIF4A promotes the cell proliferation via upregulating the ex＜x＞pression of Cyclin D1, Cyclin E2 and CDK2