The localized deformation behavior of annealed Al and Al severely deformed by ECAE process was determined by using microindentation test. Using the method proposed by Tabor, the indentation stress-strain curves of annealed Al and as-ECAE deformed Al were constructed, which display similar work-hardening behavior. For annealed Al, the altitude of the indentation stress-strain curves is a function of the indenter size. A master curve then is constructed, which displays different work-hardening behavior. For the ECAE deformed Al, the indentation stress-strain curves are independent of the indenter size, suggesting that the microstructure inside the as-ECAE deformed Al is different from the annealed Al.