Influences　of　Mn　on　hot　deformation　behavior　of　austenitic　Fe-Mn-Si-Al　alloys　were　investigated　by　hot　compression　tests　on　Gleeble　3500　thermo-mechanical　simulator　in　temperature　range　from　900　°C　to　1100　°C　and　at　strain　rate　range　from　0.01　s-1to　1　s-1.　The　results　show　that　the　peak　stress　and　the　hot　deformation　activation　energy　of　the　Fe-Mn-Si-Al　alloy　during　hot　deformation　increase　with　increasing　Mn　content.　The　hot　deformation　activation　energies　are　determined　as　361.17　kJ/mol　and　411.17　kJ/mol　for　Fe-20Mn-3Si-3Al　alloy　(20Mn　alloy)　and　Fe-25Mn-3Si-3Al　alloy　(25Mn　alloy),　respectively.　Furthermore,　the　softening　mechanism　of　the　Fe-Mn-Si-Al　alloy　during　hot　deformation　varies　with　the　variation　of　Mn　content.　The　dynamic　recovery　(DRV)　is　the　main　softening　mechanism　for　20Mn　alloy,　and　the　dynamic　recrystallization　(DRX)　is　the　main　softening　mechanism　for　25Mn　alloy　within　the　investigated　ranges　of　strain　rate　and　temperature.　The　influences　of　Mn　content　on　material　constants　in　constitutive　equations　of　both　the　alloys　were　also　determined,　and　then　the　constitutive　equations　for　the　peak　stresses　for　20Mn　alloy　and　25Mn　alloy　can　be　predicted　by　the　constitutive　equations　©　2013　Advanced　Study　Center　Co.　Ltd.