Abstract: In the research aspect of water-soil chemical interaction, more emphasis was put on the polluted water, which is under the extreme state. Unfortunately, much less studies were conducted for the soilmass stability in urban regions, which is under the ordinary state at normal temperatures, pressures and chronic change of hydrological environment. Mini-scale structure of soil plays an important role in soilmass stability, and in formation of land subsidence and soil holes in natural condition. The fracture of soil structure takes place by invalidation of the joints fetween grains and aggregates. From the view point of water-soil chemical interaction and based on mini-scale structure of soil, the authors studied the macro-deformation properties in solutions with various pH values, conducted correlative laboratory test and proved the fact that mini-scale structure is the main locations where the water-soil chemical interaction takes place