In order to investigate subgrain formation and precipitation in a 1100 aluminum alloy during hot-rolling process, DC cast ingots were subjected to four conditions of homogenization and then multi-pass hot-rolling. The size of subgrains formed during hot-rolling changed depending on the condition of rolling pass through Z-parameter, but was not affected by both the distribution of precipitates and the amout of solid solution determined by the homogenizing condition. Precipitation took place during hot-rolling. Precipitates were considered to be preferentially formed during rolling, but not formed during holding period between passes. In the present range of temperatures, the amount of precipitates increased with decreasing rolling temperature. The precipitates formed in the matix during homogenization resulted in the enhanced precipitation during rolling.