To study the characteristics of Benggang soil expansing and contracting with the moisture changes, soil samples of the red soil layer in the typical Benggang area of Anxi County, Fujian Province were collected. Through the experiment of non-charge expansion and shrinkage, non-charge expansion rates and the linear shrinkage rates of the soil samples under different initial dry densities (1.3, 1.4 and 1.5 g/cm³) and different initial soil water contents (15%, 20%, 25% and 30%) were analyzed. The results showed that the soil expansion rate was larger when the initial dry density increased in the low soil moisture. When the initial dry density was the same, the soil expansion rates decreased with the increases of initial water contents. When the initial soil moisture content was the same, the soil sample expansion rates increased as its initial dry density increased. There was a difference in the shrinkage process of soil samples with different treatments. The soil shrinkage rate with high initial water content was large, and the soil expansion and contraction processes were inconsistent and both processes were irreversible. The result revealed the relationships between soil water contents and dry densities and Benggang erosion.