The invention discloses a soil stabilizer.The soil stabilizer is characterized by comprising 30-50% of coal ash, 5-10% of slag, 5-10% of an activating agent, 0.5-1% of triethanolamine, 0.5-1% of a polycarboxylic acid compound, 0.5-1% of aliphatic series sulfonate, 2-4% of sodium sulfate, 28-50% of cement clinker and 0.5-2% of sodium fluosilicate.According to the soil stabilizer, a great amount of industrial waste is utilized, so that cost of raw materials is saved, and consumption of a traditional gluing material is reduced; the problems of industrial waste emission and environmental pollution are solved, and an active protection effect is achieved for the ecological environment.In the construction process of an overwet soil road foundation in a rainy and humid area, solidification of soil in a rainy season and overwet soil, the soil stabilizer is added easily, the process of tedding treatment is reduced under a certain circumstances, and the soil stabilizer is an ideal soil stabilizer.The soil stabilizer is simple in construction process and easy to operate, for soil in need of consolidation, according to the soil property, a certain amount of the soil stabilizer is added to soil and stirred to be uniform, compaction treatment is conducted under the optimum water content of the soil, and in other words, performance indexes such as the density degree and strength which are required by construction are reached.