The impact experiment for Mg-3Li and Mg-3Li-1Sc alloys was conducted using the Split Hopkinson Pressure Bar(SHPB) at high strain rates.The effect of minor Scandium on the impact deformation behavior and strain rate effects of Mg-3Li alloy were analyzed.The results show that the dynamic stress-strain behaviors of both alloys exhibit evident positive strain rate effect at strain rates from 1350s-1 to 3000s-1.However,the dynamic deformation behaviors of both alloys change to negative strain rate effect with the increasing strain rate.At strain rates from 1350s-1 to 3500s-1,the dynamic yield strength of Mg-3Li-1Sc alloy is enhanced significantly compared to that of Mg-3Li alloy.Under high strain rate impact loading,the strain-hardening generated by slip and twining inside grains causes the positive strain rate effect of deformation behaviors in two alloys,while the following negative strain rate effect is attribute to the initiation and propagation of micro-crack.The notable improvement of impact deformation resistance of Mg-3Li-1Sc alloy is mainly attributed to the grain refinement and the formation of small and uniformly distributed MgSc phase because minor Scandium addition.