Objective To explore the value of contrast-enhancement ultrasound(CEUS) examination in improving the diagnosis of benign and malignant breast BI-RADS types 3 and 4 tumors. methods A total of 76 breast masses confirmed by biopsy or surgical pathology were collected from 71 patients who were admitted to the Chaoyang Central Hospital in Liaoning Province from March 2019 to April 2020. All the tumors included in the study were examined by conventional ultrasound and CEUS, and were paralleled with BI-RADS classification and CEUS score. According to the CEUS score results, readjust the classification of breast BI-RADS type 3 and 4 tumors, and compare the diagnostic efficacy of the BI-RADS classification before and after adjustment to the benign and malignant breast BI-RADS type 3 and 4 tumors. Results ①Of the 76 breast lumps, 43 were benign and 33 were malignant; after adjustment, the BI-RADS classification was 7 in 2 categories, 12 in 3 categories (4 in 3 categories remained unchanged), and 20 in 4a categories (up 2 in category 3 ), 15 types 4b, 11 types 4c, and 11 types 5; the biopsy rate of BI-RADS type 4 tumors decreased to 69.8%, the misdiagnosis rate is only 1.6%. ②The sensitivity, specificity, and accuracy of BI-RADS classification diagnosis before and after adjustment were 75.8%, 76.7%, 76.3%, 97.0%, 88.4%, and 92.1%, respectively. ③The areas under the ROC curve of the BI-RADS classification before and after adjustment were 0.763 and 0.927, respectively, the difference was statistically significant (Z=3.965, P<0.05). Conclusion CEUS examination combined with BI-RADS classification can improve the diagnosis of benign and malignant breast BI-RADS 3 and 4 tumors, and reduce unnecessary biopsy of BI-RADS 4 tumors.