A novel 3D cadmium−organic framework (Cd-MOF) was prepared based on ionothermal synthesis method and successfully doped with Eu3+ cations to obtain Eu@Cd-MOF by postsynthetic modification method. Cd-MOF has a strong and stable framework due to the balance of cations on the overall structure. Using characterization methods such as powder X-ray powder diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetry analysis (TGA), these two materials have excellent solvent and chemical stability. More interestingly, both two materials can be used as multifunctional fluorescent probes to detect Fe3+, Co2+, Cr2O72−, MnO4−, and NB, and exhibit significant sensitivity, anti-interference, and recyclability. It is worth noting that compared to the original Cd-MOF, Eu@Cd-MOF enhanced excellent quenching effect on Fe3+, Co2+, Cr2O72−, MnO4−, and NB. Related to this, we conducted detailed research and discussion on possible fluorescence sensing mechanisms. This work extends propositions to the design and doped with europium of ionothermal synthesis MOFs, and explores their potential applications in the field of fluorescence sensing.