The invention provides phosphorous acid titanium with a three-dimensional open-framework structure and a preparation method thereof and belongs to the technical field of phosphorous acid titanium with a three-dimensional open-framework structure. The preparation method is characterized in that an open-framework crystal compound of the phosphorous acid titanium without an organic template is synthesized by adopting a strong acid method in a hydrothermal system, the morphology of a product is regulated and controlled by adjusting the quantities of phosphorous acid and hydrofluoric acid in reaction gel, and the phosphorous acid titanium compounds with the three-dimensional open-framework structure, which have the identical structure and are different in morphologies, are synthesized. The phosphorous acid titanium compound does not contain an organic template agent. Compared with other metal phosphorous acid salts, the phosphorous acid titanium compound has relatively good heat stability, thus favorable conditions are provided for the research of the property of the phosphorous acid titanium compound. The photovoltage research shows that the compound has the property of a p-type conductor. The invention has the beneficial effects of providing a simple, convenient and effective method for preparing the phosphorous acid titanium crystal material with the open-framework structure.