Objective: To investigate whether anti-phosphatidylserine/prothrombin antibodies and its IgG or IgM subtypes were correlated with unexplained recurrent miscarriages. Methods: In our a single-center retrospective study, 283 patients with at least one unexplained miscarriage who visited the Third Hospital of Peking University between January 2021 and August 2023, aged between 18-40 years, and tested for anti-phosphatidylserine/prothrombin antibodies IgG or IgM subtypes, were included. The patients with either positive IgG or IgM anti-phosphatidylserine/prothrombin antibody were regarded as positive for anti-phosphatidylserine/prothrombin antibody. SPSS 26.0 software was used for statistical analysis. Chi-square test and Logistic regression analysis were used to study the correlation of anti-phosphatidylserine/prothrombin antibodies and its IgG or IgM subtypes with unexplained recurrent miscarriages. And the diagnostic sensitivity, specificity, the positive predictive value, the negative predictive value of anti-phosphatidylserine/prothrombin antibodies and its IgG or IgM subtypes in unexplained miscarriages was calculated with four-fold table. Results: Chi-square analysis showed that anti-phosphatidylserine/prothrombin antibodies and its IgM subtypes were correlated with recurrent miscarriages (both P < 0.05), while the IgG subtype was not correlated with recurrent miscarriages (P>0.05). After adjusting with anticardiolipin antibodies, anti-β₂ glycoprotein antibodies, lupus anticoagulants, antinuclear antibodies, and age by Logistic regression analysis, anti-phosphatidylserine/prothrombin antibodies were correlated with unexplained recurrent miscarriages (OR=2.084, 95%CI 1.045-4.155, P < 0.05), and anti-phosphatidylserine/prothrombin antibody IgM subtypes were correlated with unexplained recurrent miscarriages (OR=2.368, 95%CI 1.187-4.722, P < 0.05).The sensitivity of anti-phosphatidylserine/prothrombin antibody in recurrent miscarriage was 65.43%, the specificity was 48.51%, the positive predictive value was 33.76%, and the negative predictive value was 77.78%. In the patients with recurrent miscarriages with negative classical antiphospholipid antibodies, the sensitivity of anti-phosphatidylserine/prothrombin antibody was 59.09%, the specificity was 63.23%, the positive predictive value was 40.63%, and the negative predictive value was 78.40%. The sensitivity of the anti-phosphatidylserine/prothrombin antibody IgM subtype for the diagnosis of recurrent miscarriage was 65.43%, the specificity was 50.99%, the positive predictive value was 34.87%, and the negative predictive value was 78.63%. Conclusion: Anti-phosphatidylserine/prothrombin antibody and IgM subtype antibody are correlated with unexplained recurrent miscarriages in patients with at least one unexplained miscarriage. Whether positive anti-phosphatidylserine/prothrombin antibody or IgM subtype could predict future unexplained recurrent miscarriages warrants a prospective study.