Ionizing radiation can lead to DNA double-strand breaks, resulting in rapid phosphorylation of histone H2AX to γ-H2AX at the location of double-strand breaks. The number of focal points formed at γ-H2AX aggregations in cells can be applied to the evaluation of DNA double-strand breaks, and is correlated with the radiation dose. Therefore, γ-H2AX can be used as a biomarker to evaluate the mutagenicity of ionizing radiation. It can also be used as a biological dosimeter of ionizing radiation to estimate individual exposure dose. Conventional detection methods of γ-H2AX aggregations include enzyme linked immunosorbent assay (ELISA), Western blot and indirect immunofluorescence assay (IFA), the fluorescent focus of which can be detected by fluorescence microscopy and flow cytometry. Through the investigation of literatures in the past ten years, most of the research work focus on the decrease of sample volume, the development of super-resolution microscopy to obtain sharper images of γ-H2AX aggregations, various image analysis softwares to achieve automation detection and new detection techniques. Research on automation/portable devices is critical to realize point-of-care testing for radiation accident emergency response and medical treatment. In terms of rapid radiation dose estimation and radiation emergency triage, the establishment of a rapid, accurate, portable and automated high-throughput γ-H2AX biological dosimetry is one of the most important research directions. As a biomarker of ionizing radiation in the future, γ-H2AX detection technology has important application value in radiation biology research, radiation molecular epidemiology, radiation accident emergency response and medical treatment. This paper discusses the research progress and application prospect of detection methods based on ionizing radiation biomarker γ-H2AX.