High flowing C30 alkali activated slag and fly ash based concrete(ASFC) was prepared in which slag and fly ash were activated by NaOH(NH) and Na2CO3(NC). Dynamic splitting tensile and compression tests were made by the 100 split Hopkinson pressure bar(SHPB) apparatus improved by using the pulse shaper technique, and damage characteristics of ASFC under impact loading were measured. In addition, a comparative study was made. The results indicate that, fracture morphology of ASFC tends to be serious and energy absorbing capacity of ASFC increases with the increasing of incident energy average rate, however, increase rate gradually become slow, and general rule can be expressed by quadratic polynomial curve; fracture state of ASFC under the condition of impact compression is more significant than that under the condition of impact splitting tension, and energy absorbing capacity and increase rate under the condition of impact compression are greater than that under condition of impact splitting tension. Thus it can be seen that damage resistance of impact increase with increasing of impact strength; compared with the condition of impact splitting tension, damage resistance of impact of ASFC is better.