Based on 3‐(2,4‐dicarboxylphenyl)‐6‐carboxylpyridine ligand (H 3 dpcp), a lanthanide metal–organic framework with the porous three‐dimensional structure was successfully synthesized, namely, [Eu (dpcp)(H 2 O)] n ( 1 ). The experimental results indicated that complex 1 exhibited stable luminescence in the range of pH = 2–11 in aqueous solution. It is noteworthy that complex 1 could recognize tryptophan (Trp) and trans, trans‐ muconic acid ( tt ‐MA) molecules through the fluorescence quenching effect, and showed high sensitivity, selectivity, recoverability, anti‐interference, and low detection limits for the identification of Trp and tt ‐MA in aqueous solution. In addition, the fluorescence mechanisms of complex 1 for sensing of tt ‐MA and Trp were elucidated in detail.