A light bridge is observed not only at photospheric and chromospheric temperatures, but also has significant emissions of coronal lines. We detect periodic emission intensity perturbations above the light bridge in the SDO/AIA 193 A and 211 A channel. The period is about 45 second and is only found at two edges of the bridge. The distribution of sub-minute oscillations in coronal lines are co-spatial with two flanks of the bridge, where magnetic shear (electric current) is strong, so it is very likely that periodic magnetic reconnections are triggered at the interfaces of two magnetic fields of the sunspot and the light bridge.