Abstract: The strengthening, toughening and fracture behavior of composite white cast iron which was composed of reinforcement steel bar and white cast iron have been researched. The results of bend tests and impact tests of specimens of composite white cast iron indicated that the bending strength and impact toughness of it were superior to those of straight white cast iron. The improvements of bending strength and impact toughness were related to the volume fraction of reinforcement bar. Three fracture modes of steel bar in composite white cast iron were found by examining the surfaces of fracture by SEM. Those were brittle fracture, ductile fracture and mixed fra- cture, and thus the different strength and toughness of composite white cast iron were effected.