The swelling of lymph nodes in the neck caused by breast cancer has no obvious morphological features in the early stage and may only be slightly enlarged, but with the progress of the disease, it may manifest as a fixed and not easy to be pushed mass, which needs active treatment. Enlargement of lymph nodes in the neck caused by breast cancer is mainly due to the spread of tumor cells to lymphatic tissues and malignant hyperplasia. Early morphological features are not obvious, and it may only be slightly enlarged, which manifests as a painless lump with irregular edges, which can be fused with each other and is not easy to be pushed. After lymph node metastasis occurs, the disease can be treated by surgery, radiotherapy, targeted drug therapy, and by actively cooperating with doctors to receive standardized treatment, the tumor lesions can be significantly reduced, the survival time of patients can be prolonged, and the prognosis of the disease can be improved. When breast cancer is found, patients should actively consult regular hospitals for early diagnosis and early treatment.