Abstract: The butt joints of FeCrAl alloy were welded by flash light welding. The microstructure, distribution of oxide particles and mechanical properties of the welded joints were investigated by scanning electron microscope and energy dispersive spectrometer. The results show that: the microstructure of FeCrAl alloy welded by flash light welding is mainly equiaxed grain. No obvious oxides are aggregated and segregated in the grain boundary of weld metal and heat-affected zone. Most oxides are dispersed in the grain and grain boundary. The tensile strength of the welded joint reaches 594 MPa, which is 90.5% of the strength of the base metal. The joint is fractured in the weld zone and presents the brittle fracture mode as a whole. The grain coarsening of the weld metal makes the hardness decrease, which leads to the softening of the welded joint.