Rare earth metal organic framework material capable of being used for detecting Fe < 3 + > in water body

The invention relates to a rare earth metal organic framework material for detecting Fe < 3 + > in a water body. The preparation method comprises the following steps: S1, selecting raw materials including rare earth salt and 1, 3, 5-benzene tricarboxylic acid; s2, dissolving 1, 3, 5-benzene tricarbonic acid in absolute ethyl alcohol, and stirring; s3, adding rare earth salt solutions with different contents into the solution obtained in S2, and stirring; s4, standing, centrifuging, washing and drying to obtain a rare earth metal organic framework material; and S5, characterizing and detecting the obtained rare earth metal organic framework material. According to the invention, 1, 3, 5-benzene tricarboxylic acid with a symmetrical structure and a plurality of coordination sites is selected as an organic ligand, rare earth ions are taken as a central body (lanthanum ions are taken as a matrix, and europium ions are taken as an activating agent) to form a rare earth metal organic framework material, and the rare