The　effect　of　relaxation　time　in　hyperbolic　heat　transfer　model　on　the　temperature　field　of　microwave　ablation　of　atrial　fibrillation　was　investigated.　And　the　results　were　compared　with　those　calculated　by　Pennes　model.　A　three-dimensional　model　of　microwave　ablation　of　atrial　fibrillation　was　constructed.　The　relaxation　time　(τ)　was　0,　1,　5,　8,　10,　15　and　20　s,　respectively.　And　the　temperature　field　of　myocardial　tissue　was　obtained.　The　results　showed　that　the　highest　temperature　of　the　hyperbolic　model　was　21.8　℃　lower　than　that　of　the　Pennes　model　at　the　beginning　of　ablation.　With　the　increase　of　ablation　time,　the　highest　temperature　tended　to　be　the　same.　The　lesion　dimensions　appeared　at　3,　4,　6,　7,　8,　9,　and　10　s,　respectively　after　ablation.　Therefore,　the　influence　of　hyperbolic　model　on　temperature　will　decrease　with　the　increase　of　the　ablation　time.　At　the　beginning　of　ablation,　the　relaxation　time　will　hinder　the　speed　of　myocardial　thermal　diffusion.　The　larger　the　relaxation　time　is,　the　slower　the　speed　of　thermal　diffusion　is.　This　study　provides　a　reference　for　the　application　of　hyperbolic　model　in　microwave　ablation　of　atrial　fibrillation.　Copyright　©　2021　by　Editorial　Office　of　Journal　of　Biomedical　Engineering.