Abstract: The eastern Inner Mongolia Plateau is the nation's transitional area of different terrains, from semi-arid to semi humid. The rapid development of agriculture in the past two decades has significantly changed the groundwater circulation and soil salt accumulation conditions of the basin. This study analyzed the spatial distribution, influencing factors and ecological changes of soil water-soluble salt in the watershed of Angulinao based on the multivariate statistics. The results show that Cl^- and Na⁺ are the main anions and cations of soil water-soluble salts in the study area, which is in the early stage of soil salt accumulation. Most of the soil water-soluble salts have intense spatial variation, especially na⁺, cl^-, so₄^2-, co₃^2- with high solubility and migration have obvious accumulation effect along the groundwater flow direction. Na⁺, Cl^-, SO₄^2- contribute about 60% of the total salt content. The data show that soil salinization frequently occurs in the area where the groundwater depth is less than 1m, the groundwater salinity is greater than1g/L, and the groundwater hydraulic gradient is less than 3×10^-4. In the drainage area, the lakes dry up and the ecological environment degenerates because of the groundwater overdraft and the agricultural irrigation in the runoff area. Besides, the runoff area has the risk of secondary soil salinization.