The　temperature　distribution　in　the　region　near　a　microwave　antenna　is　a　critical　factor　that　affects　the　entire　temperature　field　during　microwave　ablation　of　tissue.　It　is　challenging　to　predict　this　distribution　precisely,　because　the　temperature　in　the　near-antenna　region　varies　greatly.　The　effects　of　water　vaporisation　and　subsequent　tissue　carbonisation　in　an　ex　vivo　porcine　liver　were　therefore　studied　experimentally　and　in　simulations.　The　enthalpy　and　high-temperature　specific　absorption　rate　(SAR)　of　liver　tissues　were　calculated　and　incorporated　into　the　simulation　process.　The　accuracy　of　predictions　for　near-field　temperatures　in　our　simulations　has　reached　the　level　where　the　average　maximum　error　is　less　than　5　degrees　C.　In　addition,　a　modified　thermal　model　that　accounts　for　water　vaporisation　and　the　change　in　the　SAR　distribution　pattern　is　proposed　and　validated　with　experiment.　The　results　from　this　study　may　be　useful　in　the　clinical　practice　of　microwave　ablation　and　can　be　applied　to　predict　the　temperature　field　in　surgical　planning.