Abstract: Coarse grains easily lead to orange peel defects and poor anodizing effect of the surface of 6061 aluminum alloy plate. By adjusting the alloy composition, hot rolling process and solid solution treatment process of 6061 aluminum alloy, the method of controlling grain size in each process was studied.The results indicate that increasing the Mn, Cr content in the alloy can refine the grain.In the process of hot rolling, the final rolling temperature and the processing rate of the final pass will affect the recrystallization degree of the surface layer of the plate.The lower final rolling temperature and processing rate of final pass can prevent the surface layer from recrystallization.In the process of solid solution, when the core of the plate reaches the solid solution temperature, it should be quenched as soon as possible to prevent the grain size of the surface layer of the plate from increasing with the heating time. The optimized process parameters to prevent coarse grain size of 6061 aluminum alloy medium thick plate were proposed.