Objective To investigate the expression and clinical value of asymmetric dimethylarginine (ADMA) in villi and peripheral blood of patients with unexplained recurrent abortion (Ursa). Methods 168 patients with URSA were selected. The patients were divided into training set (126 cases,URSA group) and test set (42 cases) at a ratio of 3:1 by using computer-generated random number method. In addition, 126 pregnant women who terminated their pregnancy in our hospital at the same time were selected as controls to compare the training set and the clinical data of the control group, as well as the ADMA expression in peripheral blood and villus tissue. The relationship between serum Ursa expression and the occurrence of Ursa was analyzed by fitting curves and threshold effect. Multivariate logistic regression model was used to analyze the independent risk factors of Ursa and construct a nomogram model. Results Compared with the control group, the expression of IL-6, IL-117, Th17, Th17/Treg, ADMA in plasma and villi increased significantly, progesterone, IL-10 and TGF-β And Treg decreased significantly (P＜0.05). IL-6, IL-17, Th17, Th17/Treg, plasma ADMA and villus ADMA were independent risk factors for URSA, while IL-10 and TGF- β And Treg were the protective factors of URSA(P＜0.05). When plasma ADMA ≥1.43 μ Mol/l, plasma ADMA increased by 0.6 μ Mol/L, the risk of pregnant women increased by 17%, and the difference was statistically significant (OR=0.115, 95%CI: 0.102~0.133, P＜0.05). When the villus ADMA ≥1.92 μmol/L, villus ADMA increased by 0.6 μmol/L, the risk of Ursa in pregnant women increased by 14%, and the difference was statistically significant (OR=1.192, 95%CI:1.085~1.302, P＜0.05). The nomogram prediction model based on independent influencing factors has high discrimination, accuracy and clinical applicability. Conclusion The increased expression of ADMA in plasma and villi of patients with URSA is an independent risk factor for the occurrence of URSA, which has a certain predictive value for the occurrence of URSA