The invention belongs to the technical filed of photocatalysis and particularly provides a Bi (III)-metal-oxygen cluster inorganic framework as well as a preparation method and an application thereof. The Bi (III)-metal-oxygen cluster inorganic framework is applied to the field of photocatalytic degradation of organic dyes, and the chemical formula of the inorganic framework is [PMo12O40Bi2(H2O)2].4H2O. The Bi (III)-metal-oxygen cluster inorganic framework is prepared with a solvothermal method, the process is simple, the purity is high, and the reproducibility is good; further, Bi resources in China are rich, polyacid raw materials are safe, non-toxic, cheap and available, the catalytic activity of metal-oxygen clusters modified with Bi (III) is improved obviously, and accordingly, the Bi-containing metal-oxygen clusters have broad prospect in the field of photocatalysis research. The Bi (III)-metal-oxygen cluster inorganic framework without grinding can be directly used in a photocatalytic degradation experiment, complete separation can be realized through simple filtering, the circulation utilization rate is high, the defects of difficulty in separation, high probability of loss of active components, low circulation utilization rate and the like of a traditional POMs (polyoxometallates) photocatalyst are overcome, and industrial application is facilitated.