This　work　attempts　to　investigate　the　effects　of　aluminum　dosage　on　the　immobilization　of　heavy　metals　in　alkali-activated　municipal　solid　waste　incineration　fly　ash-based　pastes　to　manage　hazardous　threats　in　it.　A　variable　proportion　of　metakaolin　is　used　to　achieve　different　aluminum　dosages　in　the　synthesized　pastes.　Structure,　composition,　morphology,　and　mechanical　property　of　the　prepared　pastes　are　studied　by　employing　X-ray　diffraction,　29Si　NMR,　scanning　electron　microscopy,　and　compressive　strength　measurements.　The　results　showed　that　a　5%　metakaolin-composed　paste　exhibited　the　highest　compressive　strength　(10.94　MPa).　The　addition　of　the　aluminum　dosage-converted　soluble　chloride　salt　into　Friedel＇s　salt,　subsequently,　improved　the　immobilization　of　heavy　metals.　The　toxic　characteristic　leaching　procedure　test　showed　that　a　small　amount　of　aluminum　can　improve　immobilization　dominantly　because　of　the　effective　encapsulation　ability　of　the　pastes.　The　molecular　modeling　and　simulation　analysis　illustrated　that　because　of　the　presence　of　Na+　in　it,　sodium-alumino-silicate-hydrate　(N-A-S-H)　gel　possesses　the　most　stable　molecular　orientation.　©　2020　American　Chemical　Society.