Abstract: Breast cancer is the most common malignant tumor in women. ⁹⁹Tc^m-hydrazino-nicotinamide(HYNIC)-(poly-(ethylene glycol), PEG)₄-Glu (cyclo(Arg-Gly-Asp-D-Phe-Lys(PEG₄)))₂ (⁹⁹Tc^m-3PRGD₂) is a kind of artificial synthesized molecular tracer, which can be used to SPECT/CT for breast cancer imaging. ⁹⁹Tc^m-3PRGD₂ SPECT/CT can be used for early diagnosis, accurate staging and molecular typing of the breast cancer. Selecting the treatment regimen according to the result of ⁹⁹Tc^m-3PRGD₂ SPECT/CT is helpful to reduce the mortality of patients and improve the quality of life of patients. The application progress of ⁹⁹Tc^m-3PRGD₂ SPECT/CT in the diagnosis of breast cancer is reviewed and prospected in this paper.