The invention discloses a micropore terbium-based metal-organic framework material and a preparation method and application thereof. The micropore terbium-based metal-organic framework material has the chemical formula of [Tb(L)(H2O)](H2O)3(DMF)0.75(NMP)0.75, wherein L represents 2,4,6-tris[1-(3-carboxyl phenoxy)]methyl-1,3,5-trimethylbenzene anionic ligand, DMF represents N,N'-dimethylformamide, NMP represents 1-methyl-2-pyrrolidinone, the condensed structural formula of L is as shown in the description, the metal-organic framework material is crystallized to Monoclinic, the space group is C2/c, the cell parameters are that a=30.773(2), b=9.3088(4) angstroms, c=30.411(2) angstroms, beta=111.272(8) degrees, V=8118.2(9) angstroms<3>, and the main infrared absorption peaks of the micropore terbium-based metal-organic framework material are 3,394 m, 1,656 s, 1,551 s, 1,442 s, 1,408 s, 1,238 m, 1,134 w, 1,010 m, 827 w, 772 m and 685 w. The micropore terbium-based metal-organic framework material is obvious in change of Fe<3+> ion fluorescence intensity, detection on Fe<3+> ions can be effectively conducted, the preparation technology is simple, the raw materials are low in price and easy to obtain, the condition is mild, and the material can be prepared on a large scale easily.