The invention relates to a synthesis and preparation process for a high-silicon-molybdenum ductile iron material. The synthesis and preparation process specially comprises the following steps that raw materials are prepared, and the raw materials comprise, by mass, 60%-70% of scrap steel, 25%-35% of cast iron, 1%-1.2% of silicon iron, 1%-1.3% of ferro-molybdenum and 2%-2.5% of carburant; in the raw material melting process, furnace burdens are added in three batches; all the cast iron and 1/3 mass part of scrap steel are added in the first batch of furnace burdens, 5/11 mass part of carburant and 1/3 mass part of scrap steel are added in the second batch of furnace burdens, and 5/11 mass part of carburant and 1/3 mass part of scrap steel are added in the third batch of furnace burdens; after the third batch of furnace burdens are completely molten down, all the silicon iron and ferro-molybdenum are added, and when the temperature of molten iron rises to 1400-1410 DEG C, the remaining 1/11 mass part of carburant is added in a mirror surface mode after slagging-off impurity removal; and sampling analysis, blending, tapping, nodulizing and inoculation treatment are performed until pouring is completed. According to the process, the scrap steel is used as a main raw material, and the joint carbon adding mode of middle adding and mirror surface adding is adopted for preparing high-silicon-molybdenum ductile cast iron with high strength and high impact toughness.