In order to investigate rock dynamic mechanical properties with strain rate varying from 30 s-1to 150 s-1 on amphibolites, sericite-quartz schist and sandstone, the specimens are subjected to axial impact with different projectile speeds by using the split Hopkinson pressure bar(SHPB) of 100 mm in diameter. Optimal experimental size of rock samples was verified after analyzing the stress equilibrium of different thickness cylindrical rock samples. This work has studied the mechanic properties of stress-strain curves when these three kinds of rocks are under impact loading； The dynamic compressive strength, failure modes and energy dissipation with the strain-rate and the strain-rate hardening effect are also analyzed from the perspective of material microstructure. Experimental results show that Dynamic youngs modulus of rock samples slightly increased with train-rate. The dynamic failure modes of distinct rock samples is always different, as at a lower strain-rate，the damage of sandstone appears peeling off the external radial tensile failure mode, of amphibolites is axial splitting mode；and at a higher strain-rate, sandstone appears granular crushing failure mode, of amphibolites and sericite-quartz schist are massive crushing mode. Significant strain-rate effect can be reflected by linear relation between specific energy absorption and strain-rate，as well behveen dynamic strength increase factor n and -1/3.