Objective To investigate the value of color Doppler ultrasound in the diagnosis of breast cancer.Methods From January 2014 to December 2016,100 cases of breast masses suspected as breast cancer treated in our hospital were enrolled as the experimental subjects.They were all performed with ultrasound examinations.The pathological examination results were evaluated as gold standard.The diagnostic accuracy,specificity,sensitivity,misdiagnosis rate and missed diagnosis rate of the two methods were compared.Results Of the 100 patients with suspected breast cancer,the diagnosis of breast cancer was confirmed in 84 and the other 16 patients were benign lesions by pathologic examination.The color ultrasonography results indicated that 81 cases were diagnosed with breast cancer and the other 19 cases were benign tumors.There was no statistically significant difference of the total accuracy between color ultrasound diagnosis and pathological diagnosis of breast cancer patients (P>0.05).The proportion of the morphological irregularity,low echo with calcification point,low echo,posterior echo attenuation and axillary enlargement of lymph nodes of patients in malignant tumor group with color ultrasonography were significantly higher than those of benign tumor group,the differences were statistically significant (P<0.05).The proportion of the peak systolic velocity >15 cm/s,resistance index > 0.7 and blood flow class Ⅱ-Ⅲ of patients in malignant tumor group with color ultrasonography were far higher than those of benign tumor group,the differences were statistically significant (P<0.05).The sensitivity,specificity,missed diagnosis rate and misdiagnosis rate of color ultrasonography were 96.43%,84.21%,3.57% and 15.79% respectively.Conclusion Breast cancer can be characterized by the morphological irregularity,low echo with calcification point and posterior echo attenuation in ultrasound examination.Combined with the distribution of color blood flow and the characteristics of hemodynamics,it is helpful to distinguish benign and malignant tumors,and provides the basis for clinical treatment.