In order to clarify the effects of two kinds of laser irradiation on plasma sprayed alumina coatings, microstructure, crystallization and mechanical properties of the spacemen were examined and heat conduction in the laser irradiation processes were analyzed by a finite element method. One is CW CO2 laser irradiation of low power density, and the other is pulse excimer laser irradiation of high intensity but low energy density. Al2O3 coatings were irradiated by CO2 laser with low intensity, fine structure formation composed of α- Al2O3 was confirmed and the surface roughness was improved although the hardness decreased a little. The modified layer was corresponding to the area that was heated above 1000 to 1100°C in the calculated maximum temperature distribution. It was also confirmed that the excimer laser pulse has a potential to improve the properties of surface layer to a depth of several micrometers.