Objective To study the diagnostic value of 3.0T MRI multi B diffusionweighted imaging combined with ADC in ovarian cancer. Methods The clinical data of 85 patients with ovarian tumors who were admitted to the hospital from January 2015 to December 2017 were collected and all were confirmed by surgery and pathology. MRI was performed, including MRI plain scan, diffusion-weighted imaging with multiple b values and enhanced scan. With postoperative pathological results as the golden standard, ADC values of benign and malignant lesions on diffusion-weighted images with multiple b values were compared, and ROC curve of ADC value in diagnosis of ovarian tumors on diffusion-weighted images with multiple b values were drawn. The area under the ROC curve, the maximum Youden index, the optimal threshold, sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated. Results Postoperative histopathology confirmed that in 85 cases of ovarian tumors, there were 50 cases of benign lesions and 35 cases of malignant lesions. ADC values of the benign lesion group under different b values were significantly higher than those of the malignant lesion group (P<0.05). According to the analysis of ROC curve, areas under the curve of 5 b values (50s/mm2 , 100s/mm2 , 500s/mm2 , 1000s/mm2 and 1500s/mm2 ) were 0.817, 0.840, 0.873, 0.914 and 0.882, respectively, the optimal thresholds were 1.499, 1.336, 1.240, 1.081 and 0.957, respectively, the sensitivities were 86.8%, 88.9%, 90.1%, 93.4%and 90.7%, respectively, and the specificities were81.0%, 83.4%, 85.3%, 90.2% and 88.6%, respectively. Conclusion The diffusion-weighted 3.0 T MRI with multiple b values is an important supplement for conventional MRI. The combined use of ADC value is of certain value for the differential diagnosis of benign and malignant ovarian tumors. When the b value is 1000s/mm2 , the diagnostic efficiency is the best, and the diagnostic threshold of ADC value is 1.081×10-3mm2 /s.