Abstract: 【Abstract】 Objective To investigate the role of Tumor necrosis factor receptor Ⅱ (TNFRⅡ) in preterm labor with chorioamnionitis and their gene polymorphisms in genetic susceptibility to preterm labor with chorioamnionitis in Chengdu. Methods We collected 46 cases maternal serum and partial placental tissues of preterm labor (21 cases of infectious group with chorioamnionitis, 25 cases of noninfectious group without chorioamnionitis), and 50 cases maternal serum and 20cases placental tissues of term labor in corresponding period. TNFRⅡ mRNA in placental tissue were tested by RT-PCR, maternal serum levels of sTNFRⅡ were measured by ELISA. According to preliminary studies on TNFRⅡ -196 site of the gene type, we analyze the sites of different genotypes in patients with premature placental TNFRⅡ mRNA and maternal blood levels of sTNFRⅡ difference, and with different genotypes chorioamnionitis relevance. Results In patients with preterm labor, the results of placental TNFRⅡ mRNA and serum sTNFRⅡ were no statistically significant higher in TG (GG) than in TT (P>0.05). The levels of maternal serum sTNFRⅡ and the mRNA expression of placental TNFRⅡ in preterm labor with chorioamnionitis were significantly higher than those of preterm labor without chorioamnionitis and term labor (P0.05). Close correlation was observed between the different genotypes and the chorioamnionitis（χ2=11.088, P<0.05）.The odds ratio （OR）for TG+GG genotype was 12.65,95％CI 2.359-67.848,with more than 12.65 times probability of chorioamnionitis than that of TT genotype group. Conclusion It suggested that TNFRⅡ -196 polymorphism might not play a role by affecting TNFRⅡ production in preterm labor.The site polymorphism is associated with higher serum sTNFRⅡ and placenta TNFR Ⅱ mRNA expression in patient with chorioamnionitis. It can be a useful marker for early prediction and diagnosis of preterm labor with chorioamnionitis.