Herein, a formaldehyde-modified metal-organic framework, FA/NH2-UiO-66 is facilely synthesized via one-pot solvothermal reaction. Under excitation of 365 nm UV light, the drastic fluorescence enhancement triggered by Hg2+ ions and the un-interfered signal by the coexisting metal ions renders a sensitive and specific fluorescent detection of Hg2+ ions. A low detection limit (0.0885 nM, M refers to mol L−1) and a wide linear range (0.1 nM∼40 μM) are obtained based on calculation of the fluorescence intensity versus the concentration of Hg2 ions. The mechanism of fluorescence enhancement is ascribed to the intermolecular cyclization when Hg2+ is trapped by imino group on FA/NH2-UiO-66. Moreover, the target- directed adsorption by FA/NH2-UiO-66 leads to an effective mercury separation from contaminative system, which exhibits a satisfactory adsorption efficiency of 95.42% within 50 minutes. This work thus delivers a dual-functional MOFs-based platform for visual and hypersensitive Hg2+ tracking and effective removal of the toxic heavy metal ions, showing promise in tackling the environmental problems with monitoring and remediation synchronously. Display omitted