In order to study the effect of vacancy defects on the damping performance of γ-TiAl coating, molecular dynamics (MD) was used to simulate the reciprocating vibration of γ-TiAl coating with different vacancy concentration. The changes of stress-strain, stored potential energy, dislocation line density, defect area and microstructure were compared and analyzed. The results show that with the increase of vacancy concentration, the energy consumption of γ-TiAl coating increases gradually, and the damping performance is enhanced obviously. The stored potential energy of γ-TiAl coating with different vacancy concentration changes periodically, and the range of variation decreases gradually with the increase of vacancy concentration. In the process of vibration simulation, vacancy defects will evolve into dislocation lines and other defects, resulting in increased dislocation density and defect area. The movement, evolution and annihilation of different defects are the main sources of energy consumption of γ-TiAl coating. In addition, the high altitude concentration of γ-TiAl coating produces more plastic deformation, neck shrinkage and more holes, which further increases the energy dissipation.