Considering　that　electromagnetic　radiation　has　a　potential　hazard　to　human　body,　rats　is　usually　used　to　do　long-time　exposure　experiments　instead　of　human.　It　is　necessary　to　investigate　the　distribution　of　electromagnetic　field　inside　rats　in　order　to　guide　experiment.　The　electromagnetic　field　simulation　software　HFSS　was　used　in　the　paper　to　analyze　the　distribution　of　electromagnetic　field　and　the　specific　absorption　rate　(SAR)　inside　rats＇　head.　Results　showed　that　most　of　the　electric　energy　was　absorbed　by　the　skin　and　skull　on　the　side　near　the　antenna,　a　quarter　of　them　penetrated　into　the　brain.　SAR　distribution　was　similar　to　that　of　electromagnetic　field,　and　decreased　with　the　distance　to　antenna.　The　results　suggest　that　rat　model　and　simulation　can　help　to　understand　the　specific　distribution　of　mobile　phone　electromagnetic　fields　inside　the　rat　head.