Abstract—Silt is a kind of material with poor engineering properties, and stabilization/solidification is an effective method to improve its engineering properties. In order to explore the effect and mechanism of silt stabilization, three kinds of admixtures (lime, cement + lime and SEU-2) are chosen to stabilize silt. Unconfined compressive strength and scanning electron microscopy (SEM) tests of stabilized silt are carried out, and then the image processing analysis software Image-Pro Plus is used to quantitatively measure the values of some main microstructure parameters from SEM images. Stepwise regression method is used to select five main microstructure parameters and establish the regression equation between microstructure parameters and strength. Based on the regression equation the mechanism of silt stabilization is discussed from the point of microstructure change. This study will help to better understand the mechanism of silt stabilization.