Three-point bending specimens of MgAl are loaded by MTS material testing equipment and Hopkinson pressure bar. Strength ratio of MgAl subjected to static compression loading is gained. The dynamic response of three-point bending specimen subjected to impact loading is simulated by ABAQUS finite element software. The stress distribution around crack tip is like shape of butterfly. It indicates that stress decreases quickly away from crack tip. Strain gauges are affixed at the swings of butterfly in the experiments and can experience higher strain signal. So the choice of strain gauge position is reasonable. Based on finite displacement method and the least multiplication value theory, dynamic stress intensity factors at different loading velocities are obtained. According to crack initiation time, dynamic initiation toughness is computed. The results indicate that dynamic initiation toughness of MgAl varies at different loading rates and increases with ball velocity.