<p>The morphology of the GaN heteroepitaxial layer induced by laser confined ablation (LCA) significantly impacts the yield of laser lift-off Micro-LED. During the LCA of sapphire/undoped-GaN (U-GaN), the interface status would attenuate the laser intensity and redistribute interface temperature, affecting the non-thermal damage and temperature distribution of the U-GaN. Therefore, the LCA model established in this study explicitly considers the sapphire’s laser intensity attenuation, the interface’s heat conduction, and the interface status’s effect on U-GaN non-thermal damage and temperature distribution. Three interface statuses are named laser direct ablation(LDA), LCA of the flat sapphire substrate(FSS), and LCA of the patterned sapphire substrate(PSS). Given the difficulty in measuring the high flatness ratio damage of the U-GaN, the optical morphology by LDA was used to verify the LCA model indirectly. Then, the effects of interface status on the laser intensity, electron density, surface optical properties, and electron and lattice temperatures of U-GaN were investigated based on the LCA model. The simulated non-thermal ablation damage depths in the three interface statuses are 88 nm, 40 nm, and 54 nm, respectively. The attenuated laser intensity caused by the optical properties and thickness of the sapphire would decrease the extreme electron density and the surface optical properties of U-GaN. The interface heat conduction boundary under LCA would result in a deeper electron density distribution and a higher electron temperature and lattice temperature at the U-GaN convex features. The LCA model of sapphire/U-GaN and the influence of the interface status on U-GaN non-thermal ablation can guide optimizing the laser lift-off and improve the Micro-LED lift-off yield.</p>