Different concentrations（0-9%） of inorganic salts,such as NaCl，MgSO4，NaOH,were added into the ethanol-water system,and principal component analysis（PCA） was used to analyze the LF-NMR（T2） relaxation characteristics of the samples.The results indicated that the type and concentration of the inorganic salts could change the relaxation characteristics of the ethanol-water system.For the inorganic salt-water system,there was only one relaxation peak,and the relaxation time followed the order like this,MgSO4>NaOH>NaCl.When the inorganic salt was added into the water-ethanol system,two relaxation peaks appeared on the map,and the relaxation peaks of NaCl/NaOH-ethanol-water system appeared at 200-330 ms and 1300-1600 ms,while that of MgSO4-ethanol-water system located about 250-335 ms and 1620-1707 ms.After principal component analysis on the LF-NMR data,good differentiations among inorganic salt,water system and ethanol-water system could be found.And the distribution of samples moved regularly on the principal component scores with the increase of concentration.Therefore,the LF-NMR relaxation characteristics could be used to reflect the interaction of inorganic salt in water and ethanol-water systems with the aid of PCA.