To　improve　the　quality　of　thick　powder　bed　and　realize　the　matching　of　thick　powder　bed　and　thin　powder　bed　in　the　later　stage,　the　influence　of　process　parameters　for　the　single-track,　multi-layer　fabrication,　relative　density,　surface　quality,　defect,　remelting,　and　boundary　optimization　performance　of　different　layer　thicknesses　of　Ti-6Al-4V　fabricated　by　selective　laser　melting　were　investigated.　It　is　more　conducive　to　the　stable　forming　of　single-track　when　the　point　distance　is　half　the　diameter　of　the　laser　beam,　and　the　exposure　time　is　appropriately　extended.　The　thin　powder　bed　needs　the　corresponding　point　distance　and　exposure　time　under　the　laser　power　of　280-380　W　to　obtain　high-density　specimens.　The　thick　powder　bed　needs　to　be　able　to　ensure　the　formation　of　high-quality　specimens　under　the　smaller　point　distance　and　longer　exposure　time　under　higher　laser　power　of　380　W.　Both　thick　powder　bed　and　thin　powder　bed　will　cause　un-melted　defects　between　molten　pools,　spheroidization　defects　caused　by　splashing,　and　microporous　defects.　The　remelting　process　can　significantly　improve　the　surface　quality　of　the　formed　specimen,　but　the　surface　quality　of　the　thick　powder　bed　is　worse　than　that　of　the　thin　powder　bed.　The　boundary　quality　of　thick　powder　bed　is　worse　than　that　of　thin　powder　bed,　and　the　boundary　shape　has　a　greater　influence　on　the　quality　of　the　SLM　forming　boundary.　Different　strategies　should　be　adopted　to　form　the　boundary　of　different　shapes.　Increasing　the　boundary　count　and　increasing　the　laser　power　are　more　conducive　to　the　improvement　of　boundary　quality.