Abstract: By changing initial moisture content, compaction density and overlying load, a series of indoor loaded swelling experiments were carried out on Nanning expansive soils, and the time-history characteristics as well as its variation law of loaded swelling under different initial conditions were obtained. Further based on Sigmoid's excitation function, a swelling time-history model that considers the coupling effects of initial water content, compaction density and overlying load was established, and the relevant model parameters were determined. The analysis showed that the physical meanings of the model parameters are explicit, and the calculated results are in good agreement with the experimental results, which verifies the validity of the model. The research results can provide a reliable theoretical basis for the calculation of swelling deformation of expansive soils under overlying load.