Abstract: Objective To discuss the diagnostic value of color Doppler ultrasonography in breast diseases with thyroid diseases. Methods From January 2016 to December 2018, total 150 female patients with breast malignant tumors (breast malignant tumors group), benign breast lesions (breast benign lesions group) and healthy breast patients (breast health group) were enrolled into this study using block method according to the order of admission, with 50 cases in each group. All patients in the three groups were examined by two-dimensional and color Doppler ultrasonography to diagnose thyroid diseases. The detection rate of hypoechoic thyroid nodules, the volume of thyroid gland and the mean of hemodynamic indexes of both sides of thyroid gland were investigated. The measured indexes included the diameter of thyroid artery (D), peak systolic blood flow velocity (SPV), mean blood flow velocity (MV), diastolic blood flow velocity (DV), acceleration time (AT) and deceleration time (DT). Results Compared with the healthy breast group, the proportion of hypoechoic thyroid nodules was higher in malignant breast cancer group and benign breast lesion group (P<0.05). Compared with healthy breast group, thyroid volume in malignant breast cancer group and benign breast lesion group increased significantly (all P<0.05). Compared with the other two groups, the thyroid volume increased more significantly in breast cancer group (P<0.05). Compared with the healthy breast group, the thyroid hemodynamic indexes D, SPV and DV increased, while AT and DT decreased in the malignant breast group (all P<0.05); SPV increased in the benign breast lesion group, while AT and DT decreased (all P<0.05). Compared with benign breast lesions, SPV and AT and DT in malignant breast tumors were higher than those in benign breast lesions (all P<0.05). Conclusion Breast diseases and thyroid diseases are related and interacted. Clinical screening and diagnosis of breast diseases combined with thyroid diseases by means of ultrasound imaging has practical significance for evaluating the complications and prognosis of breast diseases.