Abstract: Taking the Nanyang medium expansive soil as the research object, the evolution laws of the swelling force and swelling rate of unsaturated remolded soils under different initial conditions (including suction, water content and dry density, etc.) are explored through indoor one-dimensional swelling characteristic tests and soil-water characteristic tests. The test results show that under different initial water contents, the unloaded expansion rate has a power function relationship with the initial suction, and this function relationship has nothing to do with the initial dry density. The swelling force increases as a power function with the increase of the initial dry density, while the swelling force first increases and then decreases with the increase of the initial water content. The swelling force has a power function relationship with the initial dry density and final water absorption. A three-variable model for the initial dry density-final water absorption-swelling force is given. A unified model for the initial water content-initial dry density-initial suction-swelling force within the full suction range is established. The proposed model has few parameters and unified left and right dimensions of the equation, and it has good consistency with the experimental data, which is convenient for engineering application. The research results provide a reliable theoretical method for the analysis of the swelling characteristics and soil-water characteristics of the unsaturated Nanyang expansive soil.