Abstract: Objective: To investigate the significance of molybdenum target in inspecting breast hypoechoic mass. Methods: Sixty-five cases with breast hypoechoic mass diagnosed by ultrasound were detected by mammography of molybdenum target. Results: Seventeen cases with non-clear lesions and 23 cases with breast hyperplastic mass were regularly followed-up. Twenty-five cases were opertated, which included 15 cases of breast cancer,5 cases of fibroadenoma,3 cases of breast adenosis,1 case of papilloma and 1 case of fibrous tissue proliferation complicated with inflammatory cell infiltration. The diagnostic accuracy rate of the dense type,many and few gland type of breast cancer was 43% and the diagnostic accuracy rate of the degeneration type of breast cancer was 82%. The clustered minute calcification was found in 7 cases of 25 cases. Conclusions: The molybdenum target examination for breast hypoechoic mass can improve the diagnostic accuracy rate of mass.