Abstract: In this study,fluorescent microsphere nanoparticles were used as immune label to develop fluorescent microspheres immunochromatographic quantitative assay for detection of aflatoxin B₁ in Semen cassiae. The results showed that the linear range and the sensitivity of the fluorescent microspheres immunochromatographic quantitative assay was 0.1~2.0 and 0.034 ng/mL,respectively. The detection methods had the advantages of rapidity and simplicity,could meet the rapid and quantitative need of the on-site screening process.