Through the blending test, it has proved that the bonding strength of Cement-Stabilized Soil (CSS) could be improved while microcrystal was mixed into as addition agent. According to the indoor test, the fracture model of CSS has been established. The Analyses showed that fracture toughness of CSS was generally increased after the proper microcrystal being added into it.In this paper, the microscopic appearance of CSS has been discussed by means of the SEM picture of CSS, and the fractal model of bending cracks for CSS has been established based on the proper hypotheses, then the microscopic toughening and crack arrest mechanisms of microcrystal addition agent to CSS have analyzed.