Laser micro-processing is an enabling technology that facilitates component miniaturization and improved performance characteristics. Alumina ceramic is used in microelectronics in printed circuit fabrication, due to its good dielectric property. Ablation is usually a combination of evaporation and melts expulsion. Material processing with laser is favour because it provides non-contact, low heat input precise method for the formation of small holes with low taper and smooth wall structure. In this study, we report the results of the micro drilling application of alumina ceramic using nanosecond laser for different wavelengths (532 nm and 355 nm) in vacuum and atmosphere environment. The effects of power, wavelength and ambient pressure on crater structure were examined.