©　2016　Nova　Science　Publishers,　Inc.　The　thermal　fatigue　or　thermal　shock　is　well　known　as　an　important　damage　mechanism　in　safety　injection　system　of　pressurized　water　reactor　(PWR).　When　the　safety　injection　system　works　due　to　the　temperature　fluctuation　or　loss　of　coolant　accident　(LOCA),　some　components　in　PWR　will　subject　to　the　thermal　fatigue　or　thermal　shock,　and　this　will　affect　the　integrity　of　the　reactor　system.　These　components　may　be　the　safety　injection　nozzle　in　reactor　coolant　system,　or　even　the　pressure　vessel.　So　it　is　very　important　to　evaluate　the　system　integrity　when　the　safety　injection　works,　and　as　a　basis　of　evaluation　the　flow　and　heat　transfer　characteristics　must　be　understood.　In　recent　years,　a　hydraulic　test　facility　was　built　with　high　flow　rate　at　Xi’an　Jiaotong　University.　With　this　test　facility　a　series　of　model　experimental　study　were　carried　out　to　investigate　the　flow　and　heat　transfer　characteristics　related　to　the　thermal　fatigue　or　thermal　shock　issue.　The　local　heat　transfer　coefficient　and　near　wall　temperature　were　got　for　different　components　in　PWR.　These　results　provide　important　basis　for　the　corresponding　mechanism　analysis　and　integrity　evaluation.