Bi12TiO20 photocatalyst doped with Fe element was prepared by hydrothermal method, and the structure of Bi12TiO20 was modified by X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance (UV-Vis DRS), scanning electron microscope (SEM), nitrogen adsorption and desorption, X-ray photoelectron spectroscopy (XPS) to characterize the morphology, microstructure and chemical valence state of the photocatalyst, and apply it to the photocatalytic degradation of methylthionine chloride (MB).The experimental results show that When the doping amount of Fe is 5%,the catalyst dosage is 0.05g, and the degradation rate of 10mg/L MB reaches 98.949%. After Fe doping, the Fe-Bi12TiO20 photocatalyst forms a new hybrid energy level, and the absorption band boundary is red-shifted, thereby improving the photocatalytic activity of the catalyst. Fe is a crystal doped in Bi12TiO20 with +3 and +2 valences middle.Fe-Bi12TiO20 photocatalyst, after repeated use for 5 times, the degradation rate of MB can still reach more than 88%, and it has excellent photocatalytic stability performance.Both h+ and·O2-are the main active species during photocatalytic degradation.This paper provides a reference for the doping modification of Bi12TiO20 materials.