Abstract: In order to determine the valid plane-strain threshold stress intensity K_ISCC of low-strength and high-toughness steel 16Mn, this paper described a kind of WOL specimens modified dimensions in surface. For such specimens, all requirements of dimensions for present criterions were satisfied and the dimensions of specimens were yet not too large. The results of test showed that 16Mn steel is less sensitive to stress-corrosion cracking in H₂S environment.