Abstract: As an effective method for treating soft soil foundations, the overload preloading method is widely utilized in projects with stringent requirements for post-construction settlement. To investigate the sub-consolidation deformation characteristics of soft soil during various stages of overload preloading, including unloading rebound and reloading operations—especially the rebound and sub-consolidation deformation features post-surcharge removal—simulations of in-situ soil compression conditions during the construction process of overload preloading treatment for soft soil foundations were conducted. Additionally, one-dimensional consolidation creep tests were performed on the soft soil of Anxiang, Dongting Lake. The results indicate that during the overload preloading stage, the compression curve of soft soil exhibits an evident boundary between primary and secondary consolidation, and the curve in the secondary consolidation stage is nearly straight. With the increase of preload, the secondary consolidation coefficient gradually decreases. In the unloading rebound stage, the rebound peak and the time required to reach it linearly increase with the preload unloading increment ratio, and a corresponding calculation formula is proposed. The removal of overload can delay, but not prevent, the secondary consolidation deformation of soil. The secondary consolidation coefficient is notably influenced by the precompression load, showing a gradual increase with the precompression load. During the reloading stage, the curve connection lines in the primary and secondary consolidation stages gradually flatten out, and the secondary consolidation coefficient decreases with the increase of the applied load. The secondary consolidation coefficient of soft soil treated by overload preloading is significantly reduced, demonstrating that the overload preloading method can effectively control settlement after construction.