To determine the parameters needed for calculation, the impact on the titanium plate edge from steel sphere is numerically simulated based on the data from test. Then, a kind of aero-engine compressor blade is taken for example，the impact damage on the blade from steel sphere is studied. During the study, the elastic plastic with kinematical hardening model is adopted and the ANSYS／LS-DYNA is used to simulate the maximum state of the blade in take-off and landing. In order to quantitatively describe the damage law, the relative kinetic energy is introduced. The effect on the impact damage from mass and relative speed is able to be reflected by the relatively kinetic energy. Besides, for the given blade, the relationships between the relatively kinetic energy and the damage depth/width are exponential and the critical damage energy of the blade is 6.6 J.