Anti-HER2 single domain antibody will be labeled with 99mTc and 188Re to prepare 99mTc-NM-02 and 188Re-NM-02, respectively. 99mTc-NM-02 is used as a diagnostic agent for SPECT/CT imaging of HER2 expression, and 188Re-NM-02 is used as a therapeutic drug for radionuclide therapy of HER2-postive Breast Cancer.