Objective To investigate the clinical value of ultrasound guided-core needle biopsy (US-CNB) in differential diagnosis of different pathological types of breast inflammatory lesions. Methods Sixty four patients with suspected mastitis in the First Affiliated Hospital of Jinzhou Medical University from September 2017 to February 2019 were selected as the subjects. All patients underwent US-CNB after Color Doppler ultrasound examination, and the pathological results after resection of the lesion were obtained by selective operation. The pathological results were obtained after resection of the lesion. The purpose of this study was to analyze and compare the accuracy of US-CNB and Color Doppler ultrasound and using postoperative histopathological findings as the gold standard for diagnosis. Results In 64 patients with suspected mastitis, the diagnostic accuracy of US-CNB was 96.9% (62/64) and that of Color Doppler ultrasound was 75.0% (48/64) compared with the pathological results after operation. The diagnostic accuracy of US-CNB was significantly higher than that of Color Doppler ultrasound (P?