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　(MM)　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)　＜　7%,　a　25　mg　MeHg/g　of　maximum　adsorption　capacity,　50　times　of　recycling,　and　without　obvious　interference　of　other　ions.　Combining　with　capillary　electrophoresis-inductively　coupled　plasma　mass　spectrometry　(CE-ICP-MS),　it　can　be　used　for　the　accurate　detection　of　ultra-trace　methyl　mercury　in　natural　water　samples　with　a　limit　of　detection　of　0.084　pg/mL,　a　recovery　of　92-99%　and　a　RSD　(n　=　5)　＜　8%.　The　success　of　this　study　promises　a　valuable　technique　for　relatively　simple　detection　of　ultra-trace　methyl　mercury　in　aqueous　environment.　(C)　2017　Elsevier　B.V.　All　rights　reserved.