The influence of dual phase microstructure and TiAlN films on the fatigue mechanism of TiAl intermetallic alloy coated with TiAlN film by the physical vapor deposition (PVD) was studied in vacuum at 1073 K from the view point of mesoscopic size which is 1 μm-1 mm size range. The crack initiation and crack growth was observed and photographed under high resolution condition using elevated-temperature loading cyclic stage for the scanning electron microscope. The results indicated that the fatigue strength of coated TiAl alloy was higher than that of uncoated TiAl alloy at an elevated temperature. TiAlN films reduced plastic deformation and crack initiation in γ phase. Therefore the fatigue process of coated TiAl alloy was dominated by initiation and growth mechanism of some mesocracks, which is 200-300 mm length. The fatigue property of coated TiAl was controlled by meso-structure, which was composed of films and substrate.