To improve the strength of silty clay-cement mixed soil, a cement-soil mixed wall is formed by making it work together with steel bars or sections. In this paper, taking the powdered clay soil in Nanchang area as an example, based on the existing research on the performance of cement soil improver, indoor unconfined compressive strength test and permeability test were conducted on the mixed soil formed by 16 groups of silty clay improvement schemes through selecting suitable curing agents and using orthogonal test to study the effects of different ratios of cement, water glass, gypsum and quicklime on the strength performance of the improved silty clay. The results were analyzed by the range analysis and variance analysis. The results showed that the compressive strength of the mixed soil was influenced by the amount of cement, water glass, gypsum and quicklime in descending order, and the optimal ratio of cement, water glass, gypsum, quicklime and naphthalene water reducing agent was determined to be 24%, 6%, 2%, 0 and 1.5%, and was recommended to be used when the water-cement ratio was 1.5 and the moisture content of the silty clay was 12%. After screening the curing agent and optimizing the proportion, the strength of the silty clay could reach 8.6 MPa at the standard age of 28 d. Finally, the microstructure of the high -strength silty clay -cement mixed soil was analyzed by scanning electron microscope test, and the mechanism of the generation of high-strength cement mixed soil was elaborated.