Abstract: OBJECTIVE To investigate the effect of human cytomegalovirus active infection on the activity of MMP9 and TIMP1 in villi cells of early pregnancy. METHODS Healthy pregnant women, who volunteered for abortion at the Xiangtan maternal and child health care hospital and the First people's hospital of Hengyang from October 2016 to October 2018 were recruited and their villi were collected. Villi cells were infected by Human cytomegalovirus (HCMV). Immunohistochemical technique was used to detect the expression of CK7, Vim and c-erbB-2 to observe the purity of villi cells, and Pp65 antigen was used to discriminate cells infected with HCMV from them. Western Blot, fluorescence quantitative PCR and ELISA were used to detect the expression levels of MMP9 and TIMP1 in villi cells of early pregnancy after HCMV infection. RESULTS Immunohistochemical staining showed that the isolated primary cells were high purity of villi cells and HCMV could infect the primary early pregnancy villi cells. Fluorescence quantitative PCR showed the mRNA expression of MMP9 in the HCMV group was 0.23±0.08, which was significantly lower than that in the control group (P<0.05). MRNA expression of TIMP1 was 5.49±1.76, which was significantly higher than that in the control group (P<0.05).Four days after the infection, the protein level of MMP9 in the HCMV group was 0.18±0.08, which was significantly lower than that in the control group (P<0.05), whereas the protein level of TIMP1 was 0.97±0.16, which was significantly higher than that in the control group (P<0.05). Besides, the protein activity of MMP9 in marophage cells infected with HCMV was consistently decreasing. Seven days after infection, the MMP9 protein level in the supernatant of the HCMV group was was significantly lower than that in the control group (P<0.05). On the 4th day and 7th day after infection, the TIMP1 protein level in the supernatant of the HCMV group were significantly higher than that in the control group (P<0.05). CONCLUSION HVMV infection could significantly down-regulate the mRNA expression and protein level of MMP9 in the early pregnancy villus cells and up-regulate the gene expression and protein level of TIMP1.