DNA fluorescent probe stains has the advantages of fast, good repeatability, less sample quantity and no radiation, compared with the traditional isotope detection. It has been widely used in automatic DNA sequencing, antibody immunoassay, disease diagnosis, anti-cancer drug analysis and so on. The sensitivity of DNA stain is an important factor affecting the detection results. Therefore, developing a more sensitive stain and avoiding the interference of biological fluorescence background has become a research hotspot.