The effects of processing parameters on surface recarburization of bainite wear-resistant steel castings with different shapes were examined in lost foam casting, and the mechanical properties of the castings were measured. Meanwhile, the effects of lost foam casting process on the mechanical properties of the castings were approached by comparing mechanical properties of rack in sand casting and in lost foam casting. The results reveal that the surface recarburization is closely related to the casting structures including shape and size, specific area, gating system, initial carbon content in molten steel as well as pattern density. The un-uniformity of surface recarburization in the castings is responsible for the heterogeneous mechanical properties in lost foam casting. Compared with that of ones in sand casting, the surface hardness of the castings in lost foam casting is obviously improved with good impact toughness.