Abstract: Objective： To investigate the relationship between uterine effusion and lower genital tract infection in patients with early threatened abortion. Methods： 80 patients with early threatened abortion admitted in our hospital from January 2017 to October 2017 were enrolled. According to whether had uterine effusion， they were divided into the observation group and the control group， 40 cases in each group. 40 patients who had uterine effusion were included in the observation group， and 40 patients without uterine effusion were included in the control group. The test of bacterial vaginosis (BV)， trichomoniasis， vulvovaginal candidiasis(VVC)， and chlamydia trachomatis (CT)， Mycoplasma (UU) were performed in both groups， and cervical secretions were cultured and their results were compared. Results： 8 cases of VVC， 4 cases of trichomoniasis， 12 cases of UU， 3 cases of CT， 7 cases of BV were detected in the observation group， 34 cases in all， the infection rate was 85%.There were 6 cases of VVC， 2 cases of trichomoniasis，10 cases of UU， 1 case of CT and 3 cases of BV were detected in the control group， 22 cases in all， and the infection rate was 55%. There was statistically significant of the difference between two groups(P<0.05). Conclusion： The incidence of lower genital tract infection in patients with early threatened abortion who has uterine effusion is greater than that in patients with early threatened abortion who without uterine effusion.