Abstract: OBJECTIVE To analyze the value of infectious indexes detection in the early diagnosis and screening of histologic chorioamnionitis（HCA） in patients with twin pregnancy and premature rupture of membrane（PROM）. METHODS Eighty patients with twin pregnancy and PROM in the First Affiliated Hospital of Hainan Medical College were enrolled, and divided into the HCA group and non-HCA group according to the presence or absence of HCA. Fifty normal full-term pregnant women with twin pregnancy who underwent cesarean section during the same period were enrolled as the control group. The serum samples were collected from each group to detect the levels of infectious indexes, including C-reactive protein（CRP）, interleukin 6（IL-6） neutrophil ratio（NEU）, procalcitonin（PCT） and white blood cell count（WBC）. Meanwhile, tumor necrosis factor alpha（TNF-α） in vaginal secretions was detected. The correlation between above indexes and the severity of HCA was analyzed. The early diagnostic value of infectious indexes for HCA was assessed by receiver operating characteristic（ROC） curves. RESULTS The serum CRP, IL-6 and PCT and TNF-α levels in vaginal secretions in the HCA group were significantly higher than those in the non-HCA group and control group（P＜0.05）. The serum CRP, IL-6, PCT, NEU, WBC and TNF-α levels in vaginal secretions were the highest in the severe group（P＜0.05）, followed by moderate group and mild group（P＜0.05）. Serum CRP, IL-6, PCT, NEU, WBC and TNF-α levels in vaginal secretions were positively correlated with the severity of HCA（P＜0.05）. ROC analysis showed that the sensitivity and specificity of CRP, PCT, IL-6 and TNF-α levels in vaginal secretions for the early diagnosis of HCA were（73.8%, 85.2%）,（71.5%, 89.6%）,（62.8%, 82.9%） and（60.5%, 72.3%）, respectively. The sensitivity and specificity of the combined diagnosis of the three was 81.3% and 92.6%, respectively. CONCLUSION After the occurrence of HCA in patients with twin pregnancy and PROM, serum CRP, IL-6, PCT and TNF-α levels in vaginal secretions are abnormally elevated. The detection of these indexes can provide reliable basis for early diagnosis of HCA, and the efficiency of 4 combined diagnosis detection is higher.