Most　of　the　existed　numerical　simulation　researches　of　MSWI　process　focus　on　combustion　stage,　few　on　the　characteristics　of　the　particles　material　generated　by　combustion.　In　this　article,　an　800t/d　mechanical　grate　type　MSWI　process　in　Beijing　took　as　the　research　object,　and　a　3D　model　are　built　to　study　and　analyze　the　particle　material　diffusion　process.　Firstly,　the　process　information　of　the　3D　model　obtained　from　the　CAD　design　drawing　in　terms　of　the　actual　MSWI　process.　Then,　by　taken　the　second　and　third　channels　as　objects,　a　3D　model　built　to　study　and　analyze　the　effect　of　baffle　length　on　the　trapping　of　particles　inside　the　channels.　Finally,　a　3D　model　of　incinerator　and　horizontal　flue　built　to　further　study　and　analyze　the　effect　of　baffle　length　on　the　trapping　of　particles　in　the　passage.　The　simulation　results　show　that　the　trapping　effect　increases　with　the　baffle　length.　More　detailed　research　should　be　made　in　the　future　study.　©　2023　IEEE.