The effect ofrare earth(Re)and titanium(Ti)multi-modification on the impact wear behavior of Mn-B high-Si bainitic cast steel was investigated systematically.The experiments show that the impact wear resistance can be improved greatly with the addition of Re and Ti.Its wear loss is only about 1/3-1/2 as large as that of the unmodified bainitic cast steel.By the Re/Ti modification,coarse dendrite grains and bainitic/martensite duplex structure have been refined effectively,and the impact toughness ofthe bainitic cast steel is nearly tripled(10mm×10 mm×55 mm with unnotched sample).Consequently,the modified bauutic cast steel possesses good wear resistance under high impact.For both modified and unmodified bainitic cast steels,high hardness white layer and deformed zone are developed beneath the worn surface under the lugh impact wear,but the formation and propagation of cracks are different for these bainitic casting steels.Different models for the formation and propagation of cracks for both modified and unmodified bairutic cast steels under high impact wear are proposed.