Abstract: The influence of annealing temperature on microstructures and mechanical properties of the 25Mn-3Si-3Al-TWIP steel was studied in this paper.The results showed that the steel had better comprehensive mechanical properties when the annealing temperature was 1 000℃.The tensile strength of the steel is about 640 MPa and the yield strength is higher than 255 MPa,while the elongation is above 82%.The microstructure is composed austenitic matrix and annealed twins at room temperature,at the same time,a significant amount of annealed twins and stacking faults are observed by TEM.Mechanical twins play a dominant role during deformation and result in excellent mechanical properties.