Soil salinization has become one of the most serious problems that affect the development of agricultural production in Yellow River irrigation areas of the central north Ningxia. As a key development of new irrigated area in irrigation project of Ningxia Hui Autonomous Region, soil salinization problem in Hongsibu has become an important issue that need for urgent improvement. The paper correctly analyzed the relationship of soil salinization with groundwater depth, geology and hydrology. Meanwhile, the WET soil moisture meter (hereinafter referred to as WET) was first applied to test ECp(pore water conductivity) in Hongsibu irrigated area, and evaluate soil salinization distributing characteristics. The results show that in Hongsibu, groundwater depth gradually becomes deeper from north to south, TDS concentration gradually decrease from north to south, and the salinity gradually reduces from north to south. Soil salinization is much more serious in lower groundwater depth and high TDS areas. This theory can be verified in Hongsibu Town, Haizi tang and the source and upper reaches of Tianshui River, where the salinity reaches the maximum and soil salinization is serious, and the source and upper reaches of Tianshui River belongs to heavily salinized area.