Abstract: The tension tests of five experimental steels were conducted, and then the engineering yield ratio, true yield ratio and static toughness were obtained. The deformation energies of the five steels before and after necking and the static toughness were also calculated by the mathematical expression of static toughness. The calculated static toughness was compared with the experimental value. The results show that the values of true yield ratios were about 13% lower than those of engineering yield ratios. The experimental values of static toughness coincided well with the calculated values. Based on the sufficient static toughness, the true yield ratio was more objective and more meaningful than the engineering yield ratio as a safety index for high strength pipeline steels.