Abstract: Study the disintegration characteristics of the soil to guide the project construction. According to the geotechnical engineering specification for soil classification standards, select different graded distribution of soil, sandy silt、clay silt and silty clay, each has two samples to do the disintegration characteristic researchs, Conelusions can be drawn as follows:(1) at the start of the disintegration process, the disintegration speed was fast, small dispersed particles at the surface of the samples fell into the water, this phenomenon of sand powder was obvious. A large amount of soils fell off, the disintegrating speed was very fast. Degree of sand particle size was larger, the porosity and permeability of soil were larger, so the disintegrating speed was faster, the two specimens nearly completely collapsed in 1 h. Clay silt has sandy silt and silty clay, the disintegrating speed is between sandy silt and silty clay. The disintegration time of silty clay samples was longer, disintegrating process was relatively slow, even its couldn't collapse a few days later; (2) the disintegration process was not a regular process, physical properties were related, and in the process of disintegration, samples collapsed in different ways. Mainly started with small powder and fragmental, Started to crack after immersing for a long time, with the increasing of fracture with powder during caving, soils cracked in blocks, bubbles escaped, water was dturbidity.