The　present　study　aimed　at　investigating　the　relationship　between　the　shape　and　size　of　ablation　zone　and　the　ablation　time　during　radiofrequency　ablation　(RFA)　at　different　tip　temperatures　(80,　85,　90,　and　95　degrees　C).　A　two-dimensional　simulation　model　of　liver　RFA　using　single-electrode　was　first　built　by　finite　element　method　(FEM).　A　closed-loop　proportional-integral　(PI)　controller　was　employed　in　the　FEM　model.　The　heat　transfer　issues　were　solved　based　on　Pennes　biological　equation.　To　improve　simulation　accuracy　of　the　FEM　models,　temperature-dependent　forms　of　the　electrical　conductivity　and　the　thermal　conductivity　were　adopted　in　the　model.　The　ablation　zone　was　assessed　by　54　degrees　C　isothermal　contour　(IT54).　The　ablation　zone　sizes　obtained　from　the　numerical　simulations　and　ex　vivo　experiments　were　compared　to　evaluate　the　validity　of　the　numerical　model.　All　the　four　tip　temperatures　(80,　85,　90,　and　95　degrees　C)　were　tested　using　3　ex　vivo　porcine　livers　respectively.　According　to　numerical　simulation　results,　the　characterization　functions　of　the　ablation　volume　and　the　ablative　margin　(AM)　were　derived.　The　proposed　curve　functions　could　precisely　characterize　the　shape　and　size　of　ablation　zone　at　different　preset　tip　values,　and　the　statistical　results　showed　that　the　prediction　curves　had　a　good　consistency　with　simulation　curves.　This　paper　proposed　the　prediction　models　of　the　ablation　zone　in　the　RFA　process,　which　could　be　used　to　achieve　accurate　planning　of　RFA　needle　placements　and　optimize　patient　care　during　temperature-controlled　RFA　therapy.