7 series duralumin alloys are widely used in aerospace and automotive fields. Tungsten inert gas (TIG) welding can be used to repair components, but the welding defects and the lack of special wire make the strength of the welding layer insufficient. In this paper, ER5356 welding wire was used to 7075-T6 alloy fusion welding, and friction stir processing (FSP) was carried out on TIG welding layer to improve the performance. The effect of rotation speed on the microstructure, mechanical properties and fracture behaviors of the welding layer was studied, with the certain TIG welding processing parameters and traveling speed. The results show that the TIG welding zone (WZ) is composed of coarse dendrites, and FSP eliminates the macroscopic defects in the WZ, significantly refines the grain size and reduces the composition difference between the stirring zone (SZ) and the base metal. The tensile fracture of TIG overlaying sample is located in the center of WZ, which has the lowest hardness and strength. FSP significantly improves the hardness and strength of the welding layer, with the fracture located in the thermo-mechanically affected zone (TMAZ) on the FSP advancing side. With the increase of rotation speed, the average grain size of SZ decreases, the strength of TMAZ and SZ increases, while the plasticity decreases.