Background:　The　aim　of　this　study　is　to　research　the　lesion　outline　and　temperature　field　in　different　ways　in　atrial　radiofrequency　ablation　by　using　finite　element　method.　Methods:　This　study　used　the　method　which　considered　the　thermal　dosage　to　determine　the　boundary　between　viable　and　dead　tissue,　and　compared　to　the　50　degrees　C　isotherm　results　in　analyzing　lesion　outline.　Besides,　we　used　Hyperbolic　equation　which　considered　the　relaxation　time　to　calculate　the　temperature　field　and　contrasted　it　with　Pennes＇　bioheat　transfer　equation.　Results:　As　the　result　of　the　comparison　of　the　lesion　outline,　when　the　ablation　time　was　120　s,　the　isotherm　of　the　thermal　dosage　was　larger　than　the　50　degrees　C　isotherm　and　with　the　increasing　of　the　voltage　the　gap　increased.　When　the　ablation　voltage　was　30　V,　the　50　degrees　C　isotherm　was　larger　than　the　thermal　dosage　isotherm　when　the　ablation　time　was　less　than　160　s.　The　isotherms　overlapped　when　the　time　was　160　s.　And　when　the　ablation　time　was　more　than　160　s,　the　50　degrees　C　isotherm　was　less　than　the　thermal　dosage　isotherm.　As　to　the　temperature　field,　when　the　ablation　voltage　was　30　V　with　the　ablation　time　120　s　the　highest　temperature　decided　by　Hyperbolic　was　0.761　degrees　C　higher.　The　highest　temperature　changed　with　relaxation　time.　In　most　cases,　the　highest　temperature　of　the　Hyperbolic　was　higher　otherwise　the　relaxation　time　was　30-40　s.　Conclusions:　It　is　better　to　use　CEM43　degrees　C　to　estimate　the　lesion　outline　when　the　ablative　time　within　160　s.　For　temperature　distribution,　the　Hyperbolic　reflects　the　influence　of　heat　transmission　speed,　so　the　result　is　more　close　to　the　actual　situation.