This study investigates on the characterization and joining behavior between glass and KOVAR alloy with fiber laser. Due to the different chemic bonds and thermal expansion coefficients, the oxide layer plays an essential role in this process. First, surface treatments under different conditions have been discussed. It’s indicated that when the two textures (the square block and the strip phase) appeared on the KOVAR surface, the joinability of KOVAR alloy enhanced. Then, considering about three laser process parameters (beam scan speed, laser power and focus position) by the orthogonal experimentation, the result indicated that the possibility of this joining technology. Finally, the fractures graphs were observed by LEXT OSL 3000. By analyzing the FeO-SiO2-Fe phase diagram and XRD on the fractures, it displayed that a new chemical substances (Fe2SiO4) had formed which was considered as the key-materials for a good glass-to-KOVAR alloy joint.