Bacillus anthracis is a highly pathogenic microorganism. Anthrax is an infectious disease caused by Bacillus anthracis, classified as Class B of our country’s statutory reporting infectious diseases. Therefore, the establishment of simple operation, rapid and sensitive detection methods for Bacillus anthracis is vital for preventing and contralling the spread of anthrax and maintaining public health security. This study innovatively proposed to synthesize soy protein gold nanoclusters (SPI-AuNCs) with strong red fluorescence emission by microwave heating using the green material soy protein as a protective agent and reducing agent.TEM, XPS, FTIR, FL, and UV-Vis characterizations were used to verify successful synthesis of SPI-AuNCs. SPI-AuNCs are spherical, which the particle size is in the range of 1.8～3.2 nm, an average diameter of 2.65 nm, and no surface plasma resonance absorption from 500 to 550 nm. The maximum excitation wavelength of SPI-AuNCs is 370 nm, and the maximum emission wavelength appears at 680 nm. The surface functional groups of SPI-AuNCs mainly include —NH, —COOH, —OH, —SH, and the element composition includes C, N, O, S, Au elements. The fluorescence of SPI-AuNCs could be quenched by the coordination between Cu2+ and surface groups of SPI-AuNCs, while DPA has a stronger chelation effect with Cu2+, which could compete for Cu2+ from the surface of SPI-AuNCs and restore the fluorescence of SPI-AuNCs. Accordingly, a new method for DPA detection based on the fluorescent “off-on” strategy was established. Under the optimal experimental conditions, the fluorescence recovery efficiency (ΔF/F1) performs a good linear relationship with DPA concentration in the range of 1.15~70.0 μmol·L-1. The linear regression equation is ΔF/F1=0.011c+0.131 with high correlation coefficient (r=0.991), and the detection limit is 0.34 μmol·L-1. In addition, the spiking experiments of the DPA in lake water and milk samples were performed. The spiked recoveries were 97.3%~103.6%, indicating that this method has great application potential in DPA detection for environmental and food samples, and can provide methodological guidance for environmental monitoring and food safety.