Compared　to　inorganic　mercury　(Hg2+),　methyl-mercury　(CH3Hg+)　and　ethyl-mercury　(C2H5Hg+)　(organic　mercury)　not　only　have　a　much　stronger　toxicity　but　also　are　more　easily　accumulated　by　marine　organisms　to　produce　bioamplification.　Therefore,　the　simultaneously　onsite　detection　of　Hg2+　and　organic　mercury　is　of　great　significance　to　ensure　the　safety　of　seafood,　and　it　is　also　a　hard　challenge.　We　designed　a　T-rich　aptamer,　H-T7,　for　specifically　recognizing　Hg2+　and　organic　mercury　and　developed　a　multicolor　aptasensor　for　simultaneous　discrimination　and　detection　of　Hg2+　and　organic　mercury　with　only　bare-eye　observation　using　H-T7　as　a　recognition　probe　and　gold　nanorods　(AuNRs)　as　a　signal.　In　the　presence　of　Hg2+　and　Ag+,　Hg2+　preferentially　and　specifically　bind　with　H-T7　immobilized　on　AuNRs　surface　and　induce　the　formation　of　a　monolayer　Ag/Hg　amalgam　on　the　AuNRs　surface　after　reduction,　resulting　in　a　change　in　color　from　orange　to　faint　purple　and　a　corresponding　shift　in　the　absorption　peak　from　820　to　730　nm　in　the　solution.　However,　in　the　presence　of　CH3Hg+　or　C2H5Hg+　and　Ag+,　CH3Hg+　or　C2H5Hg+　preferentially　bind　with　H-T7　immobilized　on　the　AuNRs　surface　and　induce　the　formation　of　a　monolayer　Ag-0　on　the　AuNRs　surface　after　reduction,　which　results　in　the　change　in　color　from　orange　to　atrovirens　and　the　corresponding　shift　in　the　absorption　peak　shift　from　820　to　670　nm　in　the　solution.　Thus,　the　inorganic　and　organic　mercury　(total　of　CH(3)Hg(+　)and　C2H5Hg+)　can　be　specifically　discriminated　and　detected　by　only　bare-eye　observation.　The　method　can　be　used　to　simultaneously　detect　inorganic　and　organic　mercury　in　seawater　by　the　bare-eye　observation　with　a　visual　detection　limit　of　2.0　ppm　for　Hg2+　and　10.0　ppm　for　organic　mercury.　The　success　of　this　study　is　a　useful　enlightenment　to　develop　an　instrument-free　method　for　an　onsite　detection　of　trace　inorganic　and　organic　mercury　in　environment　by　a　bare-eye　observation,　although　the　sensitivity　of　the　method　is　relatively　low.