Abstract: The inorganic materials adopted in the improvement of expansive soil engineering include lime and cement. During the construction process, the improving effect is greated influenced by the mixing uniformity of the soil conditioner and the soil. The above issue contains two aspects: one is the breakage of great soil aggregate in the excavation of expansive soil, the other is the reduction of high water content in the excavated soil. The method of “second mixing of lime” in cement-improved expansive soil is proposed, and the feasibility of construction process using the rotavator and strip sieve and the performing sequence of cement mixing is analyzed to provide theoretical suggestions for the the improvement of expansive soil.