An experiment on dynamic rock fracture toughness test using edge - notched disc specimen is presented. Split Hopkinson pressure bar(SHPB) with a wedge and its holder appended to the end of its incident bar is used to get high loading rate split forces; three strain gauges ar e attached along the ligament in front of the crack in order to detect initiation time and crack process; and then put the splitting force history and initiation time into finite element method to obtain dynamic fracture toughness at crack initiation. The marble specimen experiment result indicates that: a perfect splitting load can be gotten from combination of SHPB and wedge; the dynamic response of marble lags behind the load of SHPB; the crack expands fast; the dynamic marble fracture toughness of edge - notch specimen increases markedly under high loading rate, and its 5.15 MPa·m1/2 at the loading rate of 2.88×104 MPa·m1/2s-1.