Abstract: Fast multiple rotating rolling (FMRR) is used to make friction stir weld surface plastic deformation, under the effects of compressive stress and shear stress in different directions, resulting in the delivery and shear of Grain dislocations. The results show that with the rolling proceeds, the Grain on weld surface become refinement. The hardness of the base metal section within 80~90 HV range fluctuations before rolling sample, after 60 min FMRR treatment, the maximum surface hardness of about 185 HV, with increasing layer depth, the hardness value is gradually decreased. A direction perpendicular to the surface, with the distance increases from the surface, the grain size is gradually increased until it reaches the matrix grain size. After fast multiple rotating rolling. After fast multiple rotating rolling the surface hardness of the grain-refining sample has been improved significantly. That is, with the increase in the degree of grain refinement, hardness increases.