The invention discloses a preparation method of a modified BiBr visible light catalytic film, and belongs to the technical field of light catalysis .Bismuth oxide is adopted as a bismuth source and subjected to nitric acid treatment to obtain bismuth nitrate, butyl bromide pyridine ionic liquid is adopted as a bromine source, the bismuth nitrate and the butyl bromide pyridine ionic liquid are subjected to a reaction to obtain a precursor, then, a reaction is performed inside a stainless steel hydrothermal autoclave with a Teflon liner to obtain BiOBr, zeolite is treated through cationic polyacrylamide, the treated zeolite and BiOBr are subjected to a reaction inside the stainless steel hydrothermal autoclave with the Teflon liner to obtain modified BiOBr, the zeolite can be used as a light catalyst, the BiOBr is modified through addition of zeolite, the absorption band of the visible light catalyst is 570 nm or above, the absorption capacity is enhanced, and the modified BiOBr is easy to recycle .