The invention relates to a smelting method of high-toughness and high-strength casting-state ductile cast iron. The smelting method comprises the steps of 1, material selection, in which pig iron, scrap steel and a melting-back material are selected as raw materials; 2, material preparation, in which 20-40% of pig iron, 30-40% of scrap steel and 20-50% of melting-back material are selected according to percent by mass; 3, smelting, in which the raw materials prepared in the step 2 are added into a medium-frequency smelting furnace, the temperature is raised, the raw materials are molten, a carburant is added to the bottom of the furnace during smelting, and the raw materials are molten to a required furnace outlet temperature; 4, nodulization and casting, in which a nodulization pack and acasting pack are pre-heated to 600-800 DEG C before nodulization, a nodulizing agent, an inoculation agent and a coverage agent are sequentially placed in the nodulization pack placement pit, and inoculation for three times is performed; and 5, box outlet. The smelting method is simple to operate; and by adding the scrap steel and the melting-back material in a large proportion, the production cost is low, and the mechanical property is improved by a reasonable proportion.