Due　to　natural　and　production　activities,　mercury　contamination　has　become　one　of　the　major　environmental　problems　in　the　world.　Adsorption　is　one　of　the　important　means　to　solve　this　problem.　However,　most　of　the　commercially　available　adsorbents　exhibit　relatively　low　adsorption　capacity　and　slow　kinetics.　Therefore,　a　novel　4,6-diamino-2-mercaptopyrimidine-functionalised　Zr-based　metal-organic　framework　(UiO-66-DMP)　was　synthesised　in　this　study.　The　UiO-66-DMP　was　characterised　through　X-ray　diffraction,　scanning　electron　microscopy,　energy　dispersive　spectrometry,　X-ray　photoelectron　spectroscopy,　Fourier-transform　infrared　spectrometry,　and　thermogravimetric　analysis.　The　potential　of　the　UiO-66-DMP　as　a　superior　adsorbent　for　Hg(II)　removal　and　the　corresponding　mechanisms　were　evaluated　through　batch　experiments　under　different　conditions　and　density　functional　theory　calculations.　Benefitting　from　its　high　specific　surface　area　and　multiple　adsorption　sites,　the　maximum　Hg(II)　adsorption　capacity　achieved　in　this　study　was　822.00　mg.g-1,　which　is　the　highest　Hg(II)　adsorption　capacity　reported　to　date.　In　addition,　under　the　interference　of　Ca(II),　Cd(II),　Co(II),　Mg(II),　Mn(II),　Ni(II),　Cr(III),　Cu(II),　Zn(II)　and　other　coexisting　ions,　the　UiO-66-DMP　could　still　maintain　the　high　selective　adsorption　capacity　for　Hg(II).　According　to　the　characterization　analysis　and　DFT　calculation　results,　the　adsorption　of　Hg(II)　onto　the　UiO-66-DMP　was　dependent　on　electrostatic　and　covalent　interactions　between　metal　ions　and　abundant　functional　groups　on　the　UiO-66-DMP　surface.