Abstract: In view of problems such as low yield strength of low-carbon medium manganese steel and large deformation resistance of high-carbon medium manganese steel, Fe-0.25C-10Mn medium carbon medium manganese steel was prepared by adopting medium carbon (about 0.2wt%) and medium manganese (about 10wt%) and adding a certain amount of vanadium and molybdenum by induction melting, homogenization annealing, hot rolling, warm rolling at 630 ℃, cold rolling （reduction ratios of 12% and 18%）, and annealing at 630 ℃. The effect of the warm and cold rolling on the microstructure and mechanical properties of the test steel was studied. The results show that introducing cold rolling after warm rolling could eliminate the banded structure rich in carbon and manganese in the test steel, and significantly refined the structure. The microstructure exhibited characteristics of multi-phase, multi-scale and multi-morphology distribution. With the increase of the cold rolling reduction ratio, the massive structure significantly increased, and the fine strip-like structure became more obvious. The introduction of cold rolling reduced the content of residual austenite, and as the reduction ratio of cold rolling increased, the content of residual austenite decreased. At the maximum uniform tensile deformation, the residual austenite content of the test steel with a 12% cold rolling reduction ratio was the least. After introduction of cold rolling, the tensile properties of the test steel increased significantly. The higher the cold rolling reduction ratio, the larger the yield strength, and the lower the tensile strength, percentage elongation after fracture and strength-plasticity product. The process of 630 ℃ warm rolling +12% reduction ratio cold rolling could simultaneously enhance the strength and percentage elongation after fracture of the test steel; the yield strength reached 1540 MPa, the percentage elongation after fracture was close to 30%, and the strength-plasticity product was as high as 51 GPa·%, far exceeding the mechanical property requirements of the third-generation automotive steel.