A　method　for　the　detection　of　trace　As　(III),　As　(V),　monomethylarsonic　acid　(MMA),　dimethylarsinic　acid　(DMA),　arsenocholine　(AsC)　and　arsenobetaine　(AsB)　in　seaweeds　by　capillary　electrophoresis-inductively　coupled　plasma　mass　spectrometry　(CE-ICP-MS)　was　developed.　The　optimized　conditions　of　CE　including　chemical　component;　pH　and　concentration　of　the　buffer;　separation　voltage　and　injection　time　were　studied　in　detail.　The　results　showed　that　the　above　six　species　of　arsenic　were　baseline　separated　within　25　min　under　the　optimized　conditions.　The　relative　standard　deviations　(n　=6)　of　the　peak　areas　were　smaller　than　5%,　and　the　detection　limits　(calculated　as　As)　(S/N　=　3)　were　0.　08　-　0.　12　μg/L　for　all　the　above　six　species　of　arsenic.　The　method　has　been　successfully　applied　to　the　determination　of　the　species　of　arsenic　in　kelp　samples.　The　recoveries　were　90%　-　103%.　The　method　has　good　reproducibility,　high　sensitivity;　short　analytical　time　and　strong　resistance　to　complex　matrix,　and　can　be　used　for　the　speciation　analysis　of　arsenic　in　real　seafood　samples.