Adsorptive　removal　of　mercury　ion　from　wastewater　has　become　a　hot　topic　due　to　the　toxicity　and　persistence;　acquiring　adsorbent　materials　with　high-capacity,　rapid-kinetic,　super-selective　while　low-cost　features　are　highly　demanded.　Herein,　based　on　the　full　functionality　of　collagen　fiber　(CF)　from　the　leather　waste,　we　proposed　an　innovative　synthetic　approach　through　exploiting　amino-functionalized　ZIF-7　(ZIF-7-NH2)　as　functional　groups　to　facilely　in-situ　incorporate　with　CF,　affording　low-cost　but　effective　adsorbent　materials　of　CF/ZIF-7-NH2　composite　maximizing　both　functions　of　CF　and　ZIF-7-NH2　in　the　Hg(II)　capture.　Remarkably,　it　exhibits　an　ultra-high　capacity　as　high　as　909.09　mg　g-1,　fast　kinetics　that　could　remove　99.01　%　of　200　mg　&　sdot;L-1　within　20　min,　and　significant　selectivity　of　SHg/M　(KdHg/KdM)　as　large　as　522-1017　over　Mg2+,　K+,　Ca2+,　Cd2+,　and　Mn2+.　We　understand　such　an　impressive　adsorption　is　contributed　by　the　synergistic　action　between　functional　groups　including　on　the　CF　and　ZIF-7-NH2.　This　study　offers　an　effective　method　for　removing　heavy　metal　ions,　achieving　efficient　removal　of　Hg(II)　ions　for　pollution　control,　and　promoting　the　reuse　of　waste　CF　to　reduce　waste　accumulation　in　various　aspects.