An SS409M steel sheet with a tensile strength over 1400 MPa and very good, of highest quality force of meeting below toughness was got by either using controlled rolling plus air cooling or laboratorial thermo-mechanical controlled processing . The effects of CR+AC and the TMCP processes were then inspected on the microstructures and mechanical quality of this stainless steel sheet. The results showed that by using CR+AC technology an equally distributed bainitic ferrite microstructure could be produced in this steel sheet under the right reheating and rolling condition. By using TMCP technology, a thin narrow bit of bainite and martensitic microstructure with superior mechanical properties could also be generated. A micro structural analysis was made to interprete the strengthening-toughening mechanisms in connection with the processes