〔Abstract〕 Objective To research the expression of β-dystrophin(β-DG) in colon cancer cell lines(HT29,HCT116,SW480,SW620), and the effect of its overexpression on apoptosis and the expression of apoptosis related proteins in SW620. Methods Colon cancer cell lines were cultured, total protein was extracted for Western blot to detect the expression of endogenous β-DG protein in each cell. The eukaryotic expression plasmid of pcDGFP-β-DG was constructed and transfected into SW620 cells, total protein was extracted for Western blot or immunofluorescence directly to detect the overexpression and localization of β-DG. After overexpression of β-DG, the apoptosis of SW620 cells was measured by flow cytometry, and the expression of apoptotic marker protein PARP was further detected. Results Compared with normal epithelial cells HEK 293 T, the expression of endogenous β-DG(43 ku) was decreased in colon cancer cell lines, especially in SW620 cells, and different levels of β-DG hydrolysis fragments(31 ku) were detected. The eukaryotic expression plasmid pcDGFP-β-DG was constructed successfully, which could be effectively expressed in SW620 cells and mainly located in the cytoplasm near the nuclear membrane. After overexpression of β-DG, the apoptotic rate of SW620 cells was(0.167±0.014), significantly higher than that of blank group(0.075±0.027) and control group(0.084±0.023)(P<0.05). After overexpression of β-DG, the protein content of complete PARP(113 ku) decreased, and the fragment of PARP(89 ku) increased. Conclusion The abnormal expression of β-DG in colon cancer cell lines is mainly manifested in its abnormal hydrolytic breakdown. Overexpression of β-DG can significantly promote apoptosis of SW620 cells and expression of apoptotic protein, which provides a cytological basis for further understanding the function of β-DG and its relationship with colon cancer.