3003　Al　alloy　with　different　metallurgical　quality　were　obtained　by　different　melt-treatment　methods,　which　were　deformed　by　isothermal　compression　in　the　range　of　deformation　temperature　300-500°C　at　strain　rate　0.01-10.0　s　-1　with　Gleeble-1500　thermal　simulator.　The　results　show　that　the　material　is　sensitive　to　positive　strain　rate.　The　hot　deformation　activation　energy　(Q)　bears　linear　relationship　with　inclusion　content　(H)　of　3003　Al　alloy　prepared　by　different　melt-treatment,　Q=35.62　H+171.58,　the　activation　energy　of　3003　Al　alloy　prepared　by　high　melt-treatment　is　the　lowest　(174.62　KJ·mol　-1),　which　is　beneficial　to　the　material　hot　plastic　deformation.　The　critical　strain　of　3003　Al　alloy　prepared　by　different　melt-treatment　methods　is　investigated　through　the　work　hardening　rate.　Finally,　the　critical　conditions　of　the　investigated　alloy　were　determined　to　predict　the　dynamic　recrystallization　occurrence　in　the　paper.　©　(2011)　Trans　Tech　Publications,　Switzerland.