Human　Body　Communication　(HBC),　which　utilizes　the　human　body　as　communication　channel　to　convey　health　informatics,　is　a　prospective　communication　technique　for　implantable　and　surface-mounted　medical　devices.　In　this　article,　we　have　applied　Shannon＇s　theorem　to　derive　the　channel　capacity　for　the　general　galvanic　coupling　HBC　channel.　The　channel　characteristics　and　channel　model　of　general　galvanic　coupling　HBC　channel　are　firstly　discussed.　Based　on　this　channel　model,　the　channel　capacity　is　derived.　By　using　the　water-filling　algorithm,　the　HBC　channel　capacity　is　estimated　and　the　suitable　frequency　bands　for　low　power　data　transmission　in　both　on-body　and　in-body　HBC　channels　are　found.　The　results　can　provide　suggestion　for　better　system　design.