Abstract: The optical microscope and electron back scattering diffraction(EBSD) were used to comparative study the microstructure features, grain boundary characteristics and the evolution of the texture in friction stir weldedjoint and base metalof 2024/7075 dissimilar aluminum alloys. The results show that the content of low angle grain boundaryin thermal mechanical affected zoneat retreating side grain is significantly higher than that of the base metal, but there is no obvious change at advancing side. Dynamic recrystallization occurrs in stir zone, and the content of high angle grain boundary increases significantly. 2024 aluminum alloy at retreating side has a weak orientation. 7075 base metal at advancing side, heat affected zone and heat mechanically affected zone have strong S texture 123<634>, brass texture 011<211> and R texture 124<211>. Stir zone is equiaxed recrystallization grain, and has no obvious preferred orientation.