Abstract: Objective The pathological examination did not provide the basis of lesion changes after chemotherapy in patients with breast cancer.The aim of this paper is to investigate the clinical application value of color ultrasound in breast cancer patients with neo-adjuvant chemotherapy. Methods A total of 84 breast cancer patients were selected in our hospital from April,2014 to August,2016.All of breast cancer patients received treatment with neo-adjuvant chemotherapy.To compare lesion changes,hemodynamic index changes of lesion and hemodynamic index changes of abnormal axillary lymph nodes before and after chemotherapy. Results After the neo-adjuvant chemotherapy,the lesion volume decreased significantly (P<0.01),there was significant difference on lesion morphology,border,peripheral vocal cords,peripheral echo and blood flow classification (P<0.05);The pathological evaluation as the gold standard,the sensitivity was 83.02%,the specificity was 63.96% through color ultrasound;consistency of pathological evaluation and color ultrasound:Kappa=0.390,P<0.01;When compared with the values before neo-adjuvant chemotherapy,Vmax and RI of the richest Blood vessels section of lesion decreased significantly in the effective (CR+PR) group (P<0.01),there was no significant difference on Vmax and RI in the invalid (SD+PD) group (P>0.05),and Vmax and RI of the effective group was significantly lower than those in the invalid group (P<0.01);After the neo-adjuvant chemotherapy,Vmax and RI of the richest Blood vessels section of abnormal axillary lymph nodes decreased significantly in the effective group (P<0.01),there was no significant difference on Vmax and RI in the invalid group (P>0.05),and Vmax and RI of the effective group was significantly lower than those in the invalid group (P<0.01). Conclusion Color ultrasound can provide a valuable method for the assessment of efficacy in breast cancer patients with neo-adjuvant chemotherapy.