An　aluminum　alloy　used　for　can　body　stock　was　subjected　to　tension　test　at　a　strain　rates　range　of　5.56　×　10-5　to　5.56　×　10-3　s-1　and　temperature　between　223　to　773　K　to　investigate　the　effects　of　temperature　and　strain　rate　on　its　mechanical　properties.　The　serration　flow　phenomenon　is　associated　with　dynamic　strain　aging　(DSA)　and　yield　a　negative　strain-rate　dependence　of　the　flow　stress.　In　the　serrated　yielding　temperature　region　a　critical　transition　temperature　(Tt)　exists.　The　critical　plastic　strain　for　the　onset　of　serrations　has　a　negative　or　positive　temperature　coefficient　within　the　temperature　region　lower　or　higher　than　Tt.　According　to　the　activation　energy,　it　is　believed　that　the　process　at　the　temperature　region　lower　than　Tt　is　caused　by　the　interaction　between　Mg　solute　atom　atmosphere　and　dislocation.　In　the　positive　coefficient　region　two　reverse　thermal　activation　processes　occur　simultaneously.　One　is　the　solute　atoms　diffuse　to　the　moving　dislocation　and　pin　the　dislocation.　The　other　one　is　the　absorbed　resource　absorbs　the　solute　and　diminishes　the　pinning　effect.