The　effects　of　the　delivery　tube　protrusion　height　on　efficient　atomization　efficiency,　size　distribution,　sphericity　and　oxygen　content　of　Sn3Ag2.8Cu　lead-free　solder　powder　were　investigated　with　a　self-designed　supersonic　atomizer.　The　results　show　that　the　powder　with　uniform　size　distribution,　smooth　surface　and　high　sphericity　is　obtained,　and　the　higher　efficient　atomization　efficiency　and　lower　oxygen　content　for　the　powder　is　observed　when　protrusion　height　of　delivery　tube　is　4.0　mm.　the　thicker　and　more　irregular　the　intermetallic　compound　(IMC)　layers　is　observed　in　the　joint　prepared　with　Sn3Ag2.8Cu　powder　and　copper　plate　compared　with　that　with　Sn37Pb　and　copper　plate.　With　protrusion　height　of　delivery　tube　increasing　from　4　mm　to　5　mm,　the　prepared　powder　is　finer　and　the　efficient　atomization　efficiency　increases,　but　the　size　distribution　of　the　powder　deteriorates,　the　powder　surface　becomes　coarser　and　more　irregular.　With　protrusion　height　of　delivery　tube　decreasing　from　4　to　2　mm,　the　efficient　atomization　efficiency　is　significantly　decreased,　and　the　size　distribution　of　the　powder　deteriorates,　its　surface　is　coarser　and　more　irregular.　The　optimal　protrusion　height　of　delivery　tube　is　4　mm　under　the　experiment　condition.