C30 highly fluidized geopolymer concrete（HFGC） was prepared by using slag and fly ash as raw materials and NaOH and Na2CO3 as alkaline activation agent. The strength properties of HFGC under impact loading, including dynamic splitting tensile and compressive strength, were studied by using 100 split Hopkinson pressure bar(SHPB) apparatus improved with the pulse shaper technique. The results indicate that dynamic strength properties of HFGC exhibit strong strain rate dependence; for HFGC, strain rate sensitivity threshold under dynamic splitting tensile condition is 5.027s-1, and under dynamic compressive condition that is 28.89s-1, the strain rate sensitivity of dynamic splitting tensile strength is higher than that of dynamic compressive strength; the qualitative trend of dynamic strength properties of HFGC are in accord with that of normal concrete, but compared with normal concrete, the strain rate sensitivity of HFGC becomes even higher because of polycondensed network structure, and that can effectively develop the overall strength properties under impact loading. Thus it can be seen that HFGC is strain rate sensitive.