Processing of alumina ceramic substrate by laser scribing is introduced, and alumina ceramic surface gasification threshold of laser processing is analyzed based on the three-dimensional heat conduction model. A laser processing experimental platform used for alumina ceramic substrate is built with a Coherent E400 radio frequency CO2 laser and an IPG YLR-150/1500-QCW-AC fiber laser. 96% alumina ceramic substrate with the thickness within 1 mm is used for cutting and scribing experiments. The processing results are compared. During the experiment, in fiber laser continuous wave mode, breaking problems during cutting and scribing are solved by using absorbent on the ceramic surface and nitrogen as auxiliary gas. The experimental results show that 96% alumina ceramic substrate with thickness within 1 mm can be processed by cutting and scribing by using air as auxiliary gas without absorbent and with appropriate technology parameters in the qwasi-continuous wave mode.