Background:　Intra-body　communication　(IBC)　is　one　of　the　highlights　in　studies　of　body　area　networks.　The　existing　IBC　studies　mainly　focus　on　human　channel　characteristics　of　the　physical　layer,　transceiver　design　for　the　application,　and　the　protocol　design　for　the　networks.　However,　there　are　few　safety　analysis　studies　of　the　IBC　electrical　signals,　especially　for　the　galvanic-coupled　type.　Besides,　the　human　channel　model　used　in　most　of　the　studies　is　just　a　multi-layer　homocentric　cylinder　model,　which　cannot　accurately　approximate　the　real　human　tissue　layer.　Methods:　In　this　paper,　the　empirical　arm　models　were　established　based　on　the　geometrical　information　of　six　subjects.　The　thickness　of　each　tissue　layer　and　the　anisotropy　of　muscle　were　also　taken　into　account.　Considering　the　International　Commission　on　Non-Ionizing　Radiation　Protection　(ICNIRP)　guidelines,　the　restrictions　taken　as　the　evaluation　criteria　were　the　electric　field　intensity　lower　than　1.35　×　104　f　V/m　and　the　specific　absorption　rate　(SAR)　lower　than　4　W/kg.　The　physiological　electrode　LT-1　was　adopted　in　experiments　whose　size　was　4　×　4　cm　and　the　distance　between　each　center　of　adjoining　electrodes　was　6　cm.　The　electric　field　intensity　and　localized　SAR　were　all　computed　by　the　finite　element　method　(FEM).　The　electric　field　intensity　was　set　as　average　value　of　all　tissues,　while　SAR　was　averaged　over　10　g　contiguous　tissue.　The　computed　data　were　compared　with　the　2010　ICNIRP　guidelines　restrictions　in　order　to　address　the　exposure　restrictions　of　galvanic-coupled　IBC　electrical　signals　injected　into　the　body　with　different　amplitudes　and　frequencies.　Results:　The　input　alternating　signal　was　1　mA　current　or　1　V　voltage　with　the　frequency　range　from　10　kHz　to　1　MHz.　When　the　subject　was　stimulated　by　a　1　mA　alternating　current,　the　average　electric　field　intensity　of　all　subjects　exceeded　restrictions　when　the　frequency　was　lower　than　20　kHz.　The　maximum　difference　among　six　subjects　was　1.06　V/m　at　10　kHz,　and　the　minimum　difference　was　0.025　V/m　at　400　kHz.　While　the　excitation　signal　was　a　1　V　alternating　voltage,　the　electric　field　intensity　fell　within　the　exposure　restrictions　gradually　as　the　frequency　increased　beyond　50　kHz.　The　maximum　difference　among　the　six　subjects　was　2.55　V/m　at　20　kHz,　and　the　minimum　difference　was　0.54　V/m　at　1　MHz.　In　addition,　differences　between　the　maximum　and　the　minimum　values　at　each　frequency　also　decreased　gradually　with　the　frequency　increased　in　both　situations　of　alternating　current　and　voltage.　When　SAR　was　introduced　as　the　criteria,　none　of　the　subjects　exceeded　the　restrictions　with　current　injected.　However,　subjects　2,　4,　and　6　did　not　satisfy　the　restrictions　with　voltage　applied　when　the　signal　amplitude　was　≥　3,　6,　and　10　V,　respectively.　The　SAR　differences　for　subjects　with　different　frequencies　were　0.062-1.3　W/kg　of　current　input,　and　0.648-6.096　W/kg　of　voltage　input.　Conclusion:　Based　on　the　empirical　arm　models　established　in　this　paper,　we　came　to　conclusion　that　the　frequency　of　100-300　kHz　which　belong　to　LF　(30-300　kHz)　according　to　the　ICNIRP　guidelines　can　be　considered　as　the　frequency　restrictions　of　the　galvanic-coupled　IBC　signal.　This　provided　more　choices　for　both　intensities　of　current　and　voltage　signals　as　well.　On　the　other　hand,　it　also　makes　great　convenience　for　the　design　of　transceiver　hardware　and　artificial　intelligence　application.　With　the　frequency　restrictions　settled,　the　intensity　restrictions　that　the　current　signal　of　1-10　mA　and　the　voltage　signal　of　1-2　V　were　accessible.　Particularly,　in　practical　application　we　recommended　the　use　of　the　current　signals　for　its　broad　application　and　lower　impact　on　the　human　tissue.　In　addition,　it　is　noteworthy　that　the　coupling　structure　design　of　the　electrode　interface　should　attract　attention.　©　2018　The　Author(s).