A　novel　free　piston　expander　coupled　with　a　linear　generator　(FPLG)　prototype　used　in　a　small-scale　organic　Rankine　cycle　(ORC)　system,　is　presented　to　recover　the　exhaust　waste　heat　from　vehicle　engines.　On　the　basis　of　continuous　and　stable　operation　of　the　FPLG,　a　large　number　of　experiments　were　carried　out　under　different　operation　conditions.　The　effects　of　intake　pressure,　operation　frequency　and　external　load　resistance　on　the　output　performance　of　the　FPLG　as　well　as　the　motion　rule　of　the　piston　are　discussed.　The　results　show　that　both　peak　power　output　and　energy　conversion　efficiency　can　be　improved　by　increasing　the　intake　pressure　appropriately.　The　energy　conversion　efficiency　can　reach　up　to　45.82%　when　the　intake　pressure　is　0.26　MPa　and　operation　frequency　is　2.0　Hz.　With　the　increase　of　the　external　load　resistance,　the　peak　power　output　of　FPLG　shows　a　trend　of　increasing　first　and　then　decreasing.　And　the　maximum　peak　power　output　47.5　W　is　obtained　when　the　external　load　resistance　is　20　Ω　and　operation　frequency　is　2.5　Hz.　©　2018,　Editorial　Office　of　Journal　of　Xi＇an　Jiaotong　University.　All　right　reserved.