Background <p>Recent investigations reported an association between clear cell ovarian cancer(CCOC) and abnormal immune regulation, but the causal relationship among this association and specific immune cell the features needs further elucidation. The aim of the research conducted had been to investigate the potential causal impact of immune cell traits on CCOC applying a bivariate example Mendelian randomization(MR) journey.</p> Methods <p>We gathered genome-wide association study (GWAS) data on 731 categories of immunological cells and clear cell ovarian cancer from the currently published literature. To find the genetic associations between various immune cell traits and the risk of clear cell ovarian cancer, we employed inverse variance weighting (IVW) as the primary analysis technique and carried out sensitivity analyses to confirm the accuracy of the findings.</p> Results <p>This study found that six immune features were associated with an increased risk of clear cell ovarian cancer, including various T-cell and B-cell markers. The results of reverse MR analysis show that clear cell ovarian cancer can lower the level of CD3 on CD39 + resting Treg. Sensitivity analysis showed no heterogeneity or level-dependent pleiotropy.</p> Conclusion <p>This study reveals the possible genetic connected among immunophenotype and the danger of CCOC, providing new genetic ideas for understanding the connection with immune cells and clear cell ovarian cancer, while providing theoretical support for exploring the pathogenesis and immunotherapy of CCOC.</p>