【Abstract】 Objective To analyze the predictive value of ultrasound diagnosis for pathological remission and prognosis of breast cancer patients after neoadjuvant chemotherapy (NAC). Methods 82 patients with breast cancer underwent NAC and selective surgery in the hospital from March 2016 to October 2018 were selected. After chemotherapy and before operation, all patients were examined by ultrasonography. According to Mliier & Payne classification, the degree of postoperative pathological remission was divided into histological nonmajor histological response group (NMHR group) and major histological response group (MHR group). The patients were followed up for 1 year after operation, and were divided into survival group and death group according to the survival status of the patients. The differences of ultrasonic diagnostic parameters between NMHR group and MHR group, survival group and death group were compared. The receiver operating characteristic curve (ROC) was used to evaluate the predictive value of ultrasound diagnostic parameters before chemotherapy on postoperative NMHR. Logistic regression analysis and ROC analysis were used to predict the predictive value of ultrasound parameters before chemotherapy. Results The diameter of lesions and blood flow grades in the NMHR group were larger than those in the MHR group, and the pulsatility index (PI) and resistanceindex (RI) were smaller than those in the MHR group (P＜0.001). The diameter of lesions and blood flow grades in death group were larger than those in survival group, PI and RI were smaller than those in MHR group (P＜0.001). Lesiondiameter predicted the best truncation point, sensitivity, specificity, and AUC of NMHR after surgery were 6.45cm, 80.49%, 70.73%, and 0.84, respectively. The PI were 0.58, 85.37%, 78.05%, and 0.90, respectively. The RI were 0.47, 89.02%, 86.59%, and 0.93, respectively. The blood flow grades were 1.88, 80.49%, 68.29%, and 0.78, respectively. Logistic regression analysis showed that lesion diameter, PI, RI, and blood flow grades were risk factors that affected patients' death. The optimal truncation point, sensitivity, specificity, and AUC for predicting postoperative death by lesion diameter were 8.01cm, 80.00%, 76.25%, and 0.81, respectively. The PI is 0.38, 82.50%, 77.50%, 0.88, respectively. The RI is 0.25, 92.50%, 82.50%, 0.95, respectively. The blood flow grades were 2.01, 73.75%, 70.00%, and 0.75%, respectively. Conclusion Ultrasound diagnostic parameters can accurately reflect the histopathological status of breast cancer patients after NAC, Lesion diameter, PI, RI, and blood flow grading are risk factors that affect postoperative death, and have high clinical value for predicting the degree of pathological remission and prognosis after NAC.