Objective To explore the application value of contrast-enhanced ultrasound(CEUS) in evaluating the effect of neoadjuvant chemotherapy(NAC) on breast cancer.Methods Image features of 80 breast cancer patients with neoadjuvant chemotherapy were observed and analyzed by CEUS.In the process,the changes of primary foci before and after neoadjuvant chemotherapy and the changes of qualitative and quantitative indexes of blood perfusion were evaluated.The correlation between qualitative change and pathological response was also studied.Results The change of focus size measured by CEUS was higher than that of conventional ultrasound before and after neoadjuvant chemotherapy(P ＜0.05).However,there was no significant difference between the two measurements before NAC(P ＞ 0.05).All the qualitative observation indexes of the ultrasound contrast after NAC revealed obviously benign conversion(P ＜0.05).Among them,the pathological response was closely related to the changes of the enhancement degree,the distribution of the contrast agent,the order of the contrast and the contrast mode.After NAC,the perfusion parameters of the lesions showed slowly crawl and slowly retreat,low enhancement and the diminished total amount of microcirculation perfusion.Conclusions Before and after neoadjuvant chemotherapy,the changes of the lesion size deteted by CEUS were more close to the pathological evaluation than those detected by conventional ultrasound.The benign outcome of qualitative and quantitative indexes of the CEUS was more obvious than the changes of the lesion size,which had practical value for guiding the neoadjuvant chemotherapy for breast cancer,especially the CEUS indexes related to pathological assessment.