Breast cancer 21-gene testing is more credible in predicting recurrence risk and prognosis, but racial differences and domestic testing technology still have some impact. Breast cancer 21-gene test is based on the scoring of 21 breast cancer-related genes, which can predict the risk of recurrence, prognosis, and the need for adjuvant chemotherapy decision-making. A large amount of evidence-based medical evidence has confirmed the role of gene expression in breast cancer recurrence and metastasis risk, prognosis, and efficacy assessment, including 21-gene test, 70-gene test, etc. 21-gene test has the highest level of evidence-based medical grade, and it has also become the recommended use of the American Society of Clinical Oncology. However, the domestic genetic testing technology is not yet very mature, and there is a lack of industry guidelines and consensus, whether the 21-gene test results are accurate or not remains to be confirmed. Moreover, the analysis after the test in China uses the international common database and lacks the database of Chinese people, and due to the genetic differences between races, there is a lack of specificity in the analysis in China, which will also affect the accuracy of the results. It is recommended that patients should consult the doctor in time, and consider 21-gene testing when other test results make it difficult to determine the prognosis and the decision of chemotherapy, and view the results of the test in a dialectical manner.