The invention belongs to the fields of nanomaterials and solar energy photocatalysis and particularly discloses a preparation method of a strip-structured Bi5O7Br nano-photocatalytic material. The strip-structured Bi5O7Br nano-photocatalytic material is prepared from the mainly raw materials of soluble bismuth salt and a bromine-containing component by virtue of a solvothermal method, is good in crystalline state and high in purity and does not have an obvious impurity phase, and a synthesized Bi5O7Br microstructure displayed by a scanning electron microscope image is of a particularly regular strip structure. The strip-structured Bi5O7Br nano-photocatalytic material prepared by virtue of the preparation method has relatively good visible-light activity and presents high photocatalytic activity in an experiment for simulating visible light degradation of methyl orange. The synthetic method of the strip-structured Bi5O7Br nano-photocatalytic material is simple, simple and convenient to operation and beneficial to large-scale industrial production.