In this investigation, the plates of AA2024-T351 and AA7075-T651 with 5 mm thickness were butt joined by friction stir welding. The microstructural evolution in the nugget zone (NZ) of the dissimilar AA2024-7075 joints along the weld thickness direction was studied. The results indicated that the grain size of the NZ decreases from the top to the root of the joint. The fraction of dynamic recrystallization in the shoulder affected zone (SAZ) and the weld bottom is lower than that in the center of the NZ. Simple shear texture can be developed in the NZ and the texture distributions are heterogeneous. The SAZ consists of B and?B components, while A or?A components are the major textures at the bottom position. C component is found in the middle of the NZ. The texture intensity in the middle of the NZ is lower than that of at the top and bottom. This is mainly due to the presence of the onion ring, in which materials mixing occurs, resulting in a more random grain orientation.