The effect of different warm rolling temperature and cumulative reduction on microstructure and mechanical properties of a 6061 aluminum alloy sheet rolled by twin roll casting was studied. Multi-scale characterization techniques were employed to study the microstructures of cast-rolled and warm-rolled sheets. The mechanical properties such as hardness, strength and elongation were also measured. The results show that the cast-rolled 6061 alloy mainly contains heat-resistant phase e.g. Al0.7Fe3Si0.3, and Al9Fe0.84Mn2.16Si, and a small amount of strengthening phase Mg₂Si.With increasing rolling passes, the shape of second phases gradually changes from mesh and sheet shape to line shape along the rolling direction, and finally to fine granular shape. After warm rolling, the amount of a new precipitate Al0.5Fe3Si0.5 and Mg₂Si increases. Additionally, the hardness linearly increases with increasing reduction, and the maximum slope (2.42114) of hardness curves is found at the warm rolling temperature of 370℃. At this temperature, fine AlFeSi precipitates and Mg₂Si phases are uniformly dispersed in the alloy. The highest hardness of 84.28HV is obtained for plate. The tensile strength, yield strength and elongation are 29.34MPa, 79.09MPa and 20.11% respectively.