Objective To evaluate the diagnostic value of diffusion-weighted imaging(DWI) for the diagnosis of lymph node metastasis in patients with epithelial ovarian cancer. Methods The preoperative routine MR imaging, DWI (b=0,800s/mm2 ) and the ADC values of lymph node pictures of 37 cases of epithelial ovarian cancer were analyzed retrospectively. The postoperative pathology and imaging were compared, and the metastatic and non-metastatic lymph nodes were confirmed by pathology after operation. The clinical and pathological factors of the two groups were analyzed. The ADC(MeanADC, MinADC, MaxADC) values of each lymph node were measured and analyzed statistically including short-axis, long-axis and mean diameters. Receiver operator characteristic curve (ROC) was used to analyze the respective diagnostic efficiency. Results There was statistical difference in differentiation degree of tumor cell, clinical stage, vascular invasion, fallopian tube invasion, omentum majus invasion and presence of ascites between the two groups (P<0.05) and the differences between tumor site has no statistical significance (P>0.05). There was statistical difference in MeanADC, MinADC and MaxADC values, short diameter and short/length ratio of lymph nodes. While the difference in length diameter of lymph node between the two groups was not statistically significant (P>0.05).The AUC of the MaxADC (0.976) was greater than that of the other ADC-based criteria and all size-based criteria. And with 1.082×10-3mm2 / s as a threshold to identify lymph node metastasis, its sensitivity and specificity were 91.1% and 93.2%. Conclusion The diagnostic efficacy of ADC value in pelvic metastatic lymph nodes was significantly higher than that the diameter of lymph node.