The invention discloses a hazardous solid waste plasma harmless treatment system and method. According to the hazardous solid waste plasma harmless treatment system, a plasma gasification melting furnace is used for primary treatment to obtain molten slag and flue gas, and a reforming combustion chamber is used for further secondary treatment of the flue gas. According to the hazardous solid wasteplasma harmless treatment system, toxic and harmful substances such as heavy metals and the like can be advantageously recovered, the leaching concentration of the heavy metals is far lower than thetoxic leaching standard, the molten slag can be used as building materials or roadbed materials, no secondary pollution of fly ash is produced, the generation of harmful gases (such as dioxins and odors) can be effectively controlled, and harmful components in the obtained flue gas can be reduced to a lower level.