Purpose: To investigate the expression of ANXA3 in breast cancer tissues and normal breast tissues and its relationship with the clinicopathological features. Methods: The expression levels of ANXA3 mRNA and protein were determined by fluorescent quantitative RT-PCR and Western blot, respectively, in 81 samples from breast cancer tissues and normal breast tissues. Flow cytometry, used to detect the cell cycle, further analyzed the differences in the cell proliferation indexes between cancer and the normal tissues. In addition, the correlation between the gene and protein expression levels of ANXA3 and the cell proliferation indexes in breast cancer tissues was calculated. Results: The expression levels of ANXA3 mRNA and protein were significantly higher in breast cancer tissues than in control samples. Furthermore, their expression patterns were significantly different in patients with different axillary lymph node metastasis states, with or without vascular tumor thrombus, and with different molecular classifications. The expression of ANXA3 mRNA and protein in patients with triple-negative breast cancer was significantly higher than in Luminal A and B types. However, no significant differences were detected in the expression levels in other subtypes. Compared to normal tissues, the cell proliferation indexes of breast cancer tissues were significantly higher, and presented significant positive correlations with the ANXA3 gene and protein expression levels. Conclusion: The expression of ANXA3 might play a crucial role in promoting the occurrence, development, and metastasis of breast cancer. It could serve as an important marker involved in the invasion and metastasis states, and the prognosis of breast cancer.