The Suaeda salsa marsh in high tidal flat of the northern Yellow River estuary were selected as study object, and the variations of inorganic sulfur fractions during the growing season were investigated by conducting an in situ experiment of nitrogen (N) import which included four treatments (N0, no N input; N1, low N input; N2, middle N input; and N3, high N input). Results showed that the inorganic sulfur contents in soils under different treatments generally followed the order of H₂O-S > Adsorbed-S > HCl-Soluble-S > HCl-Volatile-S, and the total inorganic sulfur (TIS) contents accounted for 34.52%~39.58% of the total sulfur (TS) in the four treatments. The contents of H₂O-S, Adsorbed-S, HCl-Soluble-S and HCl-Volatile-S in wetland soil was changed by exogenous N enrichment in varying degrees, and the effects reached significant levels in some periods of the growing season (P<0.05). Compared with N0, the contents of H₂O-S increased by 6.12% and 7.07% under N1 and N2 treatments, respectively, and decreased by 0.98% under N3 treatment. The content of Adsorbed-S increased by 11.73% under N1 treatment, but decreased by 23.53% and 13.77% respectively under N2 and N3 treatments. The contents of HCl-Soluble-S and HCl-Volatile-S showed a decreasing trend under N1, N2 and N3 treatments, and the decline were 5.21%, 19.63%, 59.59% and 0.28%, 16.10%, 6.44% respectively. Soil nutrient condition, water salinity, and acid-alkali conditions under different N enrichment treatments were the key factors that affected the amount of TIS, but the effects of pH and EC on the dynamics of different inorganic sulfur fractions were especially obvious. This study found that the exogenous N enrichment could affect the absorption and utilization of inorganic sulfur fractions by altering the growth rhythm of plants and the acid-base status of soils, which consequently changed the contents of inorganic sulfur fractions and the stock of TIS in marsh soils.