In conclusion, our results demonstrated that circ-ERBB2 was highly expressed in HER2-positive breast cancer and was interrelated to Lymph node metastasis and HER2 status in patients with HER2-positive breast cancer and the circ-ERBB2 knockdown repressed HER2-positive breast cancer cell growth, preliminarily confirming that circ-ERBB2 might be a novel oncogene in HER2-positive breast cancer and we further provided novel ceRNA regulatory pathways for HER2-positive breast cancer: circ-ERBB2/miR-136-5p/TFAP2C or circ-ERBB2/miR-198/TFAP2C. The gene discussed is TFAP2C; the disease is breast cancer.