The invention discloses a system and a method for gasifying and melting solid wastes, and belongs to the technical field of environmental protection. The system comprises a solid waste feeding unit, acirculating fluidized bed gasifying unit, an entrained flow bed gasifying and melting unit, a waste heat recovery and dust removal unit and a gasified gas purification unit which are sequentially connected, the waste heat recovery and dust removal unit comprises a gasification agent preheater, a waste heat boiler, a dust remover and a gas cooler which are connected in sequence, a fly ash circulation pipeline is connected to the bottom of the dust remover, the fly ash circulation pipeline is provided with a returning unit, the circulating fluidized bed gasifying unit comprises a circulating fluidized bed gasifying furnace and a circulating fluidized bed gas-solid separator, and the returning unit is connected with the returning port of the circulating fluidized bed gas gasifying furnace. The system and the method can realize the large-scale industrial processing scale of solid wastes, and solve the problems of high energy consumption, low thermal efficiency, low gasification efficiency, poor adaptability of raw materials, incomplete harmless treatment of ash and slag, and easy entrainment of harmful substances in the smoke in existing solid waste treatment methods.