Abstract: Dispersive soil has the characteristics of low erosion resistance and easy to disperse in water. It is easy to cause accidents such as roadbed instability and dam piping. Due to the lack of the study of dispersed soils in China, there is no unified standard yet, and different identification tests often produce different results. At the same time, the different determination experiments have different grades. The dispersive degree of soil cannot be precisely distinguished. This paper takes Qian'an soil as the study samples, measures soil properties and mineral composition. It divides the crumb test, the double hydrometer test, the pinhole test and the exchangeable sodium ion test into four grades. They are high dispersive, dispersive, transitional dispersive, and non-dispersive. It gives a different score for each dispersion level. According to the weight value and score, the paper determines the dispersive degree of soil sample. This method of evaluating soil dispersion grade can be used as a reference for comprehensive judgment of dispersion grade of dispersed soil mass.