【Objective】To investigate the expression of FosB in invasive breast cancer and its correlation to the ultrasound findings and clinical significance.【Methods】Immunohistochemical and ultrasound examination were performed  for 155 cases with invasive breast cancer，36 cases with paracancerous tissue and 30 cases with normal breast tissue. To investigate the correlations between the different expression of FosB with histological grade ，lymph nodes，and ultrasound findings.【Results】①The expression of FosB in paracancerous tissue and normal breast tissue was higher than that in invasive breast cancer（P＜0.01）. ②Based on immunohistochemical staining，high positive expression rate of FosB was associated with low histological  grade，ER positive and PR positive（P＜0.05）. There was no correlation between FosB and age，tumor diameter，lymph nodes，Her2 and clinical stages（P＞0.05）③The expression of FosB was higher in microcalcification positive and lymph nodes bigger tissues（P＜0.05）. There was no correlation between FosB and tumor size， regular shape，boundary，posterior attenuation ratio and blood flow（P＞0.05）.【Conclusion】The expression of FosB in invasive breast cancer was lower than that in paracancerous tissue and normal breast tissue. The different expression of FosB was correlated with histological grade，ER positive and PR positive. To study the expression of FosB in invasive breast cancer may be helpful for differential diagnosis and targeted treatment. The different expression of FosB was correlated with microcalcification，lymph nodes，and combined FosB with ultrasound findings may contribute to prognostic evaluation of breast cancer.