Abstract: High brightness solid-state lasers,especially the fiber laser,have received extensive attention all over the world owing to their favorable comprehensive advantages,such as high beam quality,high processing flexibility,and low operating cost.In this paper,some aspects on high brightness solid laser welding physical processes,such as the transition of welding mode,laser-induced plume,spatters,the micro-morphology of the keyhole wall and the energy coupling in the keyhole are reviewed.Additionally,some new welding methods,including ultra-narrow gap laser welding of heavy section,laser penetration brazing of dissimilar alloys,and laser-arc hybrid welding,are also reviewed.