For　rapidly　and　sensitively　determining　ultra-trace　methyl　mercury　(MeHg)　in　aqueous　environment,　we　herein　synthesized　a　MeHg　ion-imprinted　magnetic　nanoparticle　(MeHg　IIMN)　to　simply　and　specifically　extract/concentrate　ultra-trace　MeHg　from　water　samples.　The　MeHg　IIMN　employed　core-shell　Fe3O4@SiO2　nanoparticles　(Fe3O4@SiO2　NPs)　as　supporting　structure,　the　complex　ion　of　1-pyrrolidinecarbodithioic　acid　and　MeHg　(PDC-CH3Hg+)　as　template,　methacrylic　acid　(MAA)　as　functional　monomer　and　trimethylolpropane　trimethacrylate　(TMPTM)　as　cross　linker.　The　MeHg　IIMN　offered　obvious　advantages　such　as　low　cost,　easy　manipulation,　better　specificity　and　stability,　and　recycling　characteristics.　It　can　be　used　to　separate/concentrate　ultra-trace　MeHg　from　natural　water　sample　within　30 min　with　a　recovery　＞95%,　an　enrichment　factor　of　250,　a　relative　standard　deviation　(RSD,　n = 5) 　©　2017　Elsevier　B.V.