The aim of this study was to produce a bimodal grain size structure in the aluminum sheet 1050, to achieve optimum conditions in terms of strength and ductility, by accumulative roll bonding (ARB) and annealing processes. For this purpose, ARB process was applied on aluminum samples from 2 to 8 cycle at ambient temperature and without lubrication. in order to achieve appropriate ductility and toughness, ARBed samples were annealed in 300°C and380 C and different time period. Microstructural changes after ARB and Anneal process, were analyzed by optical microscopy, as well as to evaluate the mechanical properties, uniaxial tensile test and hardness test were used. The microstructural studies showed a bimodal grain size distribution produced by discontinuous recrystallization under 4, 6 and 8 ARBed cycles and annealed at 300°C samples; While the temperature increases to 380°C, the normal grain growth and continuous recrystallization were accured and no bimodal structure was observed in this temperature. The effect of strain caused by different ARB cycles, showed that a minimum of applied strain (2 cycles ARB) was required to achieve bimodal structure. Among the samples examined in this study, the highest toughness was achieved in the sample with 6 ARBed cycles and 18000s annealed at 300°C. tensile strength, ductility and toughness of this sample were 83.6 MPa, 55.8% and 46.6 MJ/m 3 . The activation energy of grain growth in the range of 300-380°C, was calculated and the results showed that with increasing temperature from 300°C to 380°C, activation energy of grain growth increased from 40.8 kJ/mol to 66.4 kJ/mol. The change in activation energy was because of transmission of the growth mechanism from abnormal to normal growth. Keywords: Accumulative roll bonding, Bimodal grain size structure, grain growth activation energy