Objective: To explore a new index that predict lymph node metastasis(LNM) of ovarian cancer(OC). Design: A cross-sectional study of two medical centers. Setting: Two medical centers from Nantong, China. Sample: There were 447 patients included as the training set meanwhile 284 patients were included in the validation set. Methods: A total of 447 patients diagnosed with OC from January 2008 to June 2019 were included in this retrospective study as the training set. A total of 284 patients were included in the validation set. The optimal cut-off critical value of indicator CA125 combined with D-dimer(ICD) was evaluated by the receiver operating characteristic curves(ROC), and the maximum Youden index (sensitivity + specificity-1). Univariate and multivariate analysis were used to evaluate ICD as a predictor of LNM in OC. Main outcome measures: LNM burden. Results: According to ROC curve, area under curve(AUC) of ICD (AUC=0.706, p<0.001) was significantly larger than that of CA125 (AUC=0.671, p<0.001) and D-dimer (AUC=0.562, p=0.022) alone. Multivariate analysis showed that ICD (HR 2.651, 95% CI 1.273–5.520, p=0.009) was an independent predictor of LNM rather than overall survival(OS) in OC. It has also been verified in another medical center. Conclusions: ICD can be used to screen and predict the development process of OC. ICD is an independent predictor of LNM in ovarian cancers, which is helpful for clinicians to draw up individual treatment plans. Funding Scientific Research Project of “333 Project” in Jiangsu Province (BRA2019030). Nantong Science and Technology Foundation grant (MS22019008). Keywords: OC, CA125, D-dimer, ICD, NLM