Abstract: DNA double strand breaks(DSBs)are the gravest form of DNA damage in eukaryotic cells and it is a serious lesion that can cause genomic instability, ultimately leading to tumorigenesis.Phosphorylated histone H2AX(γH2AX)is a biomarker of cellular response to DSBs and could clearly reflect the status of DNA damage and repair and the biomarker is widely applied in the researches of cell apoptosis both in domestic and abroad.The review focuses on the research progress in the application of γH2AX-based methods to detect DNA DSBs, as well as application in early cancer screenings, assessment on the genotoxicity of environmental compounds, and evaluation of therapeutic effect of medical procedures or treatments.