A　regenerative　organic　Rankine　cycle　(ORC)　system　was　designed　to　recover　and　utilize　the　waste　heat　energy　from　engine　exhaust　gas　efficiently.　The　mathematical　model　of　regenerative　ORC　was　built　up　in　Matlab　and　the　influences　of　the　factors　such　as　suction　pressure,　evaporating　pressure　and　expander　inlet　temperature　on　system　performance　were　analyzed.　Then　the　regenerative　ORC　was　compared　with　the　basic　ORC　by　using　a　combined　first　and　second　law　analysis.　According　to　the　results,　when　the　evaporating　pressure　remained　constant,　the　regenerative　ORC　system　thermal　efficiency　and　exergy　efficiency　would　increase　at　first,　then　decrease　with　the　increasing　of　suction　pressure.　The　mass　flow　rate　increased　while　the　heat　transfer　rate　in　the　evaporator　decreased　first　and　then　increased　with　the　increasing　of　suction　pressure.　By　comparing　the　two　configurations,　it　was　seen　that　regenerative　ORC　produced　higher　efficiency　with　a　lower　irreversibility　and　could　recover　waste　heat　energy　more　effectively.