Abstract: Soft clay is a kind of bad soil to soil engineers. It is widely distributed in the Yellow River delta and its estuary areas. Bad engineering geological problems often happen in the estuarine areas which lie in the northern part of the Yellow River delta. So far, the engineering properties and the spatial distribution pattern of the soft soil in this area have remained unclear. This time, to meet the needs in socio-economic development, systematic and comprehensive investigation has been carried out based on large amount of borehole data of soft clay from the estuarine areas. Detailed probability distribution models of engineering geologic parameters and their correlations are studied in addition to the origin, thickness, burial conditions, development process and distribution of the soft soil in the study area. Main engineering geological problems and counter measures are proposed. The soft soil of the north Yellow River estuarine area is characterized by high water content, high compressibility, and low shear strength. The variation coefficient of physical properties of the soil is small and dominated by a normal probability distribution pattern. Soft soil layers, which consist of clayed soil, muck and mucky silt saturated or nearly saturated by water, cover almost 85% of the north Yellow River Delta, predominating the coastal and deltaic facies. The methods of pile foundation, desilting and replacement, stack preloading, and electrochemical reinforcement are recommended for ground treatment in the study area. The research results of this paper may provide the basis and reference to engineering construction in the Yellow River delta.