Chemical structure characteristics of dissolved lignins from sodium sulfide pretreatment and control kraft pulping were studied by the elemental analysis, 1H-NMR and 13 C-NMR spectra. The results indicate that the contents of sulfur and methoxyl group and the delignification process of sodium sulfide pretreatment kraft pulping are different from those of control pulping. The lignin removal reaction of sodium sulfide pretreatment kraft pulping has its own special rule.