The stabilized soil is a reinforcement material being applied extensively to civil engineering and hydraulic engineering. At present, chemical methods are used to improve density and strength of soil by increasing the state of inter-particles’ contacts and forces among particles or particle groups. Liquid stabilizer is the chemical reinforcing agent of stabilized soil. The physical and chemical interaction of reinforcing agent - clay - water affects the reinforcement of soil. The mechanism of strengthening soil using the Liquid stabilizer had not been clear. In laboratory, many experiments were carried out in order to study strengthening mechanism of the stabilized soil. From the result of the test and analysis of its characteristics, we recognized that the reinforcement effect of the liquid stabilizer is controlled by the mini-structure of the stabilized soil, and strength of the stabilized soil comes mainly from its mini-structure.