Highlights:　(1)　A　3D　simulation　model　of　MWA　(microwave　ablation)　based　on　the　temperature-dependent　characteristic　parameters　and　blood　flow　parameters　was　established　to　realize　the　visual　simulation　of　temperature　distribution　and　coagulation　zone.　The　internal　forced　convection　condition　was　used　to　accurately　characterize　the　large　vessel.　(2)　The　ex　vivo　MWA　experimental　platform　was　built　to　verify　the　accuracy　of　the　simulation　model.　A　peristaltic　pump　was　employed　for　operatively　controlling　blood　circulation　and　a　medical　soft　plastic　tube　was　introduced　for　appropriately　simulating　a　blood　vessel.　(3)　The　influences　of　blood　flow　parameters　of　large　vessels　on　temperature　distribution　and　coagulation　zone　were　systematically　analyzed　in　order　to　provide　reference　and　guidance　for　MWA　clinicians.　Purpose:　Clinical　MWA　of　liver　tumor　is　significantly　limited　by　the　accurate　prediction　of　vascular　cooling　effects.　To　provide　reference　and　guidance　for　clinical　MWA　of　liver　tumor,　the　three-dimensional　effects　of　different　blood　flow　parameters　of　large　vessels　on　MWA　temperature　distribution　were　systematically　evaluated.　Materials　and　methods:　Firstly,　the　MWA　threedimensional　finite　element　simulation　model　with　blood　flow　parameters　was　established.　Secondly,　to　verify　the　effectiveness　of　the　model,　MWA　was　performed　ex　vivo　in　porcine　liver　for　360　s　and　the　temperature　was　measured　by　thermocouples.　A　medical　soft　plastic　tube　was　placed　parallel　to　the　MWA　antenna　to　simulate　a　natural　liver　vessel.　Finally,　based　on　this　model,　the　influences　of　different　vessel　diameters　and　vessel-antenna　spacings　on　MWA　temperature　distribution　were　analyzed.　Results:　Sixteen　ablations　were　performed　to　verify　the　accuracy　of　the　simulation　model.　The　mean　temperature　errors　between　measured　data　and　simulation　results　at　six　measurement　points　were　3.87　degrees　C.　In　the　first　10　seconds　of　MWA,　the　vessel　cooling　effect　on　temperature　distribution　was　negligible.　When　the　vessel-antenna　spacing　was　5　mm　and　the　vessel　diameter　varied　from　3　mm　to　6　mm,　the　temperature　at　the　measured　point　near　the　vessel　decreased　by　2.11　degrees　C　at　360　s.　When　the　vessel　diameter　was　6　mm　and　the　vessel　antenna　spacing　varied　from　5　mm　to　7　mm,　the　temperature　at　the　measured　point　near　the　vessel　reduced　by　14.91　degrees　C　at　360　s.　In　addition,　blood　diameter　had　little　influence　on　the　temperature　distribution　near　the　heating　point.　The　volume　of　coagulation　zone　will　not　be　obviously　affected　once　the　vessel　lies　outside　the　predicted　coagulation　zone.　Conclusions:　The　MWA　simulation　model　with　blood　flow　parameters　is　established.　Vessel-antenna　spacing　is　the　primary　factor　affecting　the　temperature　distribution.　A　vessel　with　larger　diameter　can　have　a　more　significant　effect　on　the　temperature　distribution.　The　large　vessel　will　take　away　and　block　part　of　conduction　heat,　so　the　coagulation　zone　will　not　be　formed　on　the　lateral　side　of　the　vessel.