Municipal　solid　waste　incineration　(MSWI)　is　the　most　widely　used　solid　waste　treatment　techniques.　Dioxin　(DXN)　is　a　highly　toxic　and　persistent　pollutant　discharged　from　MSWI　process.　The　mechanism　model　of　DXN　is　difficult　to　establish　because　of　the　complex　physical　and　chemical　characteristics.　In　the　practical　industrial　process,　DXN　emission　concentration　is　off-line　detected　for　monthly　or　seasonal　periods,　which　cannot　be　used　to　operational　optimization　and　feedback　control　of　the　MSWI　process.　In　this　paper,　a　numerical　simulation　model　of　DXN　production　based　on　commercial　process　simulation　soft　ware　is　constructed　for　a　practical　MSWI　plant.　At　first,　the　production　mechanism　of　DXN　and　a　practical　MSWI　heat　and　mass　balance　process　are　given　out.　Then,　the　sensitive　analysis　of　DXN　production　with　several　key　variables　is　made　based　on　the　constructed　numerical　model.　It　shows　the　constructed　numerical　simulation　model　is　effective.　More　detailed　works　should　be　done　in　the　future.