Effects of a surface layer with chill structure, specimen thickness, shape of mold and powder lubrication in a sleeve on fracture mechanic characteristics were investigated for aluminum alloy die castings ADC12 with two different types of molds (flat and staircase shapes). The results are as follows. In the case of a flat mold, a decrease of thickness improves mechanical properties. A surface layer with chill structure has a substantial influence on mechanical properties, but little influence on fracture toughness. In the case of the staircase mold, the mechanical properties are the same as for the flat mold. On the other hand, the powder lubrication in the sleeve improves the fracture toughness and reduces the scatter in fracture toughness. There is little influence of both the surface layer with chill structure and the specimen orientation on the fatigue crack growth resistance, but with decrease of specimen thickness, the fatigue crack growth resistance decreases, especially in the region of near-threshold fatigue crack growth rate. In addition, the lubricating method has no effect on the fatigue crack growth resistance for the staircase-shapes die castings.