In　the　paper,　selective　laser　transmission　sintering　the　2%PF/silica　sand　core-shell　composite　powders　was　studied　based　on　a　developed　optical　model　by　using　a　Zemax　optical　design　program.　The　construction　of　the　powder　bed　was　made　by　the　particle　stacking　model　with　the　composite　particle　assumed　as　a　three-component　optical　system.　It　showed　that　simulation　results　agreed　well　with　the　experimental　data.　A　focus　point　after　the　first　layer　particle　was　produced　by　the　translucent　spherical　lens　of　particles　and　then　laser　beam　was　quickly　diverged　by　subsequent　particles　along　the　beam　transportation　path.　The　occurrence　of　the　vaporization　at　the　focus　point　had　little　effect　on　the　whole　properties　of　the　sintered　sample　because　of　its　relatively　small　size.　Since　no　melting　pool　was　produced　in　the　sintering　process　owing　to　the　thin　polymer　binder,　the　rearrangement　of　the　powder　bed　was　not　remarkable　which　led　to　a　constant　porosity　of　the　powder　bed　before　and　after　laser　sintering.　Laser　transmission　sintering　of　core-shell　composite　powders　was　basically　＂contaction＂　sintering,　where　particles　near　to　each　other　as　well　as　within　the　beam　transportation　path　had　an　opportunity　to　sinter　together.　(C)　2012　Elsevier　Ltd.　All　rights　reserved.