Abstract: The microstructure of as-cast, hot-rolled and intercritical annealed Fe-C-10Mn-4Al TRIP steels was observed by OM, XRD, EBSD technique, and the tensile properties in different states were tested. The results show that the main microstructure of the experimental steel is ferrite and austenite, and δ-ferrite is retained to room temperature. After hot rolling and intercritical annealing, the volume fraction of austenite in the steel reaches 89.3%, and the transformation of austenite to martensite occurs during the tensile process（transformation induced plasticity, TRIP effect）. The tensile strength of i s the ample after intercritical annealing is 757.3 MPa, the elongation is 44.9%, and the product of strength and plastic reaches 33.8 GPa·%. The strength and toughness of the experimental steel greatly improve.