Microstructure,mechanical properties and electrochemical corrosion properties of bobbin-tool friction stir welding（FSW）for the 7075 aluminum alloy were studied. The results show that,the welding zone is composed of weld nugget,thermo-mechanically affected zone,heat affected zone and base metal. The weld nugget is composed of fine equiaxed grains,the heat affected zone is composed of coarse deformed grains and the heat affected zone is coarse microstructure of base metal. Due to grain refinement and mechanical work hardening,the hardness of welding zone is markedly improved. However,the tensile strength has no significant increase,which is only 267.84 MPa. The boundary of retreating side and base metal is fuzzy,consisted of inhomogeneous mixed-grain microstructure,which is responsible for the low strength. The corrosion resistance of the surface perpendicular is better than that of the parallel to the weld joint,but the corrosion resistance of the welding zone is worse than that of the base metal.