The automobile industry pays lots of attention on a new kind of steel with excellent combination of strength and ductility as well as the lower density, aiming at developing more affordable and safe vehicles with less fuel composition and air pollution. Fe-Mn-Al steel, adding more Al and C elements into twinning induced plasticity (TWIP) steel, shows amazing mechanical properties, corrosion resistant and weight reduction than traditional steel. The mechanical properties and microstructure of Fe-27Mn-11.5Al-0.95C-0.59Si steel after hot rolling and solid solution treatment were investigated to analysis the evolution within the range of 950~1100 ℃. Based on the true stress-strain curves and corresponding strain hardening rate, the characteristic of Fe-Mn-Al steel could be obtained. The deformation mechanism was learned by comparing the microstructure and XRD after tensile deformation. The results show that, with the designed composition system, hot rolled steel has the duplex structure of austenite matrix and small amount of banded ferrite with tensile strength of 1315.6 MPa and density of 6.55 g/cm³, which achieves the research targets of high strength and light-weight. Solid solution treatment contributes to austenite growth and banded ferrite crushing. But exorbitant temperature results in coarse and higher volume fraction of ferrite, and the ductility drops as well as the strength. The tensile strength and elongation of the steel solution treated at 1050 ℃ are 925.9 MPa and 50.20%, respectively. Product of tensile strength and elongation is 46.48 GPa·%. Continuous strain hardening behavior provides Fe-Mn-Al steel with perfect combination of strength and ductility. The wider the constant hardening stage, the larger of measured elongation. With the estimated stack fault energy of 86 mJ/m², the dual phase structure of austenite and ferrite is retained after tensile deformation other than transformation induced plasticity (TRIP) or TWIP effects, and the microstructure of deformed sample, including Taylor lattice, high density dislocation wall and microband, shows the obvious characteristic of planer gliding with obvious slip bands on the surface of deformed austenite. The dislocation gliding observed by TEM is consistent with MBIP theory and should be confirmed by a mount of experiments and contrast in further.