6061 aluminum alloy was successfully processed by four-pass equal channel angular extrusion（ ECAE）through Bcroutes. Isothermal compression behavior was tested at strain rates ranging from 0. 05 to 1 s- 1and deformation temperate at 603

629 ℃. The true stress-strain curves were analyzed and semi-solid isothermal compression mechanism was described. Influences of deformation temperature and strain rate on the curves were analyzed. The results show that during the isothermal compression

solid-liquid separation occurs

and the flow stress of 6061 aluminum alloy is decreased with increasing in deformation temperature and increased with increasing in strain rates.