The influences of lattice parameter of austenite, the electron concentration, the yield strength of parent phase on γ→εmartensite start temperature Ms in the Fe-Mn alloys containing C, Al, Ge and Si have been experimentally investigated. Theresults show that the lattice parameter of austenite is more important than the electron concentration and the yield strength ofparent phase in governing the γ→εmartensitic transformation in Fe-Mn based alloys. A relation between the Ms and latticeparameter of austenite in Fe-Mn based alloys is suggested. The elements Mn, C, Al, Ge, which increase the lattice parameter The influences of lattice parameter of austenite, the electron concentration, the yield strength of parent phase on γ → εmartensite start temperature Ms in the Fe-Mn alloys containing C, Al, Ge and Si have been experimentally investigated. Theresults show that the lattice parameter of austenite is more important than the electron concentration and the yield strength of parent phase in governing the γ → εmartensitic transformation in Fe-Mn based alloys. A relation between the Ms and lattice parameter of austenite in Fe-Mn based alloys is suggested. The elements Mn , C, Al, Ge, which increase the lattice parameter