〔Abstract〕 Objective To study the effect of ubiquinol-cytochrome C reductase subunit 2(QCR2) on cell cycle arrest of cervical cancer SiHa cell line, and to explore related mechanisms. Methods The log-phase SiHa cells were taken, and QCR2 siRNA and control siRNA were transfected into SiHa cells by liposome transfection, which were set as QCR2 siRNA group and control siRNA group, and untreated cells were set as a blank group. qRT-PCR and Western blot were used to determine the relative expression of QCR2, p53 mRNA and protein. Propidium iodide(PI) staining was used to determine cell cycle. The cells in the QCR2 siRNA group were taken, and were intervened with a final concentration of 50 nmol/L ubiquitin-proteasome inhibitor PS341 as the QCR2 siRNA+PS341 group. In addition, the cells in the QCR2 siRNA group were intervened with the same amount of normal saline(NS) and set as the QCR2 siRNA+NS group. Western blot was used to determine the relative expression of p53 protein. The immunoprecipitation test was used to determine the level of p53 ubiquitination. Results Observed under a fluorescence microscope, the transfection efficiency of QCR2 siRNA group and control siRNA group were both>80%. Compared with the blank group and control siRNA group, the relative expression of QCR2 mRNA and protein in the QCR2 siRNA group decreased(P<0.05), the proportion of G0/G1increased(P<0.05), and the proportion of S, G2/M decreased(P<0.05). There was no significant difference in the relative expression of p53 mRNA between the groups. Compared with the blank group and control siRNA group, the relative expression of p53 protein in the QCR2 siRNA group increased(P<0.05). Compared with the blank group and QCR2 siRNA+PS341 group, the relative expression of p53 protein in the QCR2 siRNA group and QCR2 siRNA+NS group increased(P<0.05). Compared with the blank group and control siRNA group, the degree of p53 ubiquitination in the QCR2 siRNA group was reduced(P<0.05). Conclusion Silencing QCR2 can block SiHa cells in G0/G1phase. Its mechanism may be related to the inhibition of p53 ubiquitination and the increase of its protein expression.