A　pump-driven　loop　heat　pipe　(PLHP)　system　was　proposed　for　cooling　data　centers　freely.　Based　on　exergy　balance　equation　of　steady　flow　system　the　exergy　balance　models　of　components　for　the　system　were　established.　The　variation　and　distribution　of　exergy　loss　for　both　system　and　every　single　component　under　three　working　conditions　were　compared　theoretically　and　experimentally.　The　results　showed　that　the　largest　exergy　loss　was　from　the　evaporator,　over　40%.　The　next　was　from　the　condenser　and　the　pump,　about　25%.　The　exergy　loss　of　the　condenser　and　the　evaporator　were　mainly　caused　by　the　heat　transfer　temperature　difference.　The　exergy　loss　of　the　pump　was　mainly　from　the　deviation　of　isentropic　compression　process.　The　evaporator,　the　condenser　and　the　pump　should　be　considered　in　sequence　for　system　thermal　performance　improvement.　©　2018　International　Heat　Transfer　Conference.　All　rights　reserved.