Abstract: Orthogonal design and variance analysis methods have been used to optimize chemical composition and heat treatment parameters for good TRIP and combination of elongation and tensile strength in low carbon low alloy silicon-manganese steels. As a result, the optimum chemical composition and heat treatment parameters have been found, an excellent combination of elongation and tensile strength(TS ×T-EL=322.33 MPa·%) has been achieved in 0.28%C-1.62%Si-1.09%Mn steel at an isothermal holding temperature of 400℃ for 3 min after heating at 790℃ for 4 min.