Abstract: Experiments have been made on 16Mn steels with various contents of carbon, silicon and manganese under the condition of controlled rolling and controlled cooling. We have now measured their various mechanical properties and have made quantitative metallographic analyses for their major structural parameters such as the average diameters of their ferrite grains (d_F) and pearlite percentages(Pe%). We have made multelinear progressive regressive analyses to find out the relationships between their various mechanical properties and the contents of different elements in 16Mn steels as well as their two main structural parameters.As a result, We have obtained th formulas of quantitative relationships between the various mechanical properties of controlled rolled and controlled cooled 16Mn Steels and theire chemical compositions and structural parameters. According to the informations provided by these formulas,and referring to the mttltilinea regressive equations of the two structural parameters to the chemical compositions of steels and their technological parameters of controlled rolling and controlled cooling, we probed into the strenthen-toughening mechanism of controlled rolled and controlled cooled 16Mn steels.