〔Abstract〕 Objective To investigate the molecular mechanism by which short hairpin RNA(shRNA) interferes with silencing of collagen triple helix repeat containing 1(CTHRC1) to induce apoptosis in human breast cancer MCF-7 cells. Methods The shRNA-CTHRC1 plasmid and negative control plasmid were transfected into breast cancer MCF-7 cells. The mRNA and protein expression levels of CTHRC1 were determined by qPCR and Western blot respectively. The cell proliferation activity and apoptosis rate were detected by CCK-8 and flow cytometry respectively. The changes of mitochondrial membrane potential were detected by mitochondrial membrane potential kit(JC-10 staining). The expression of apoptosis-related proteins Caspase 3, Cyt C and p53-mediated mitochondrial apoptosis pathway related proteins p53, Apaf-1, Cleaved-caspase 9, Bcl-2, Bax and PUMA was detected by Western blot. The shRNA-CTHRC1 plasmid and si-p53 interfering plasmids were transfected into MCF-7 cells, respectively or simultaneously, and the expression levels of p53 and Cyt C protein were detected by Western blot, the apoptosis level was detected by flow cytometry. Results Silencing CTHRC1 reduced the mRNA and protein expression levels of CTHRC1, inhibited cell proliferation, promoted cell apoptosis, decreased mitochondrial membrane potential, and upregulated the protein expression levels of Cleaved-caspase 3, p53, Apaf-1, Cleaved-caspase 9, Bax, PUMA and the cytoplasm protein of Cyt C in MCF-7 cells, while down-regulated the protein expression levels of Bcl-2 and the mitochondrial Cyt C in MCF-7 cells. However, interference with p53 expression could reverse the pro-apoptotic effect of CTHRC1 silencing on MCF-7 cells. Conclusion CTHRC1 silencing is dependent on the p53-mediated mitochondrial apoptosis pathway to induce apoptosis in human breast cancer MCF-7 cells.