To improve the housing lifetime, insulation reliability and assembly consistency, the process and breakdown characteristics of a ceramic packaged multi-gap gas switch used for fast linear transformer driver (FLTD) were studied based on the multi-gap gas switch with stackable insulators and electrodes. The effects of different sealing processes on the electric field distribution of the interface between ceramic and metal were compared and analyzed, then the reasonable sealing structure was optimized. A ceramic packaged multi-gap gas switch was designed and its self-breakdown and triggering characteristics were experimentally tested. The results show that when the switch operates at the charging voltage of ±100 kV, the gas pressure of about 0.3 MPa and the peak current of 30 kA, the average delay time of 5 000 shots is 36.4 ns and the jitter is 2.8 ns. The ceramic package gas switch has the advantages on productization and maintenance-free, and will have broad application prospects in FLTD module.