ABSTRACT: The current research is concerned with a study on the effect of vacuum preloading conjunction with conventional surcharge loading for soft soil improvement experimental and numerical. Several experimental tests were performed by using a large-scale consolidometer were performed to examine the effect of vacuum and to determine parameters such as the extent of smear zone and the soil permeability characteristics. The experimental tests studied numerically using the method of finite elements. The settlement and excess pore pressure associated with a combined vacuum and surcharge load indicate that applying a vacuum has significant effect. The results indicated that the water content decreased with radial distance and the hydraulic conductivity in the smear zone of the PVD increased due to using vacuum pressure. Also, the time required to reach at certain degree of consolidation decreased with using vacuum preloading. Large-scale consolidometer and numerical simulation can be used in the preliminary design works which may reflect the influence on the cost estimate of the used of vacuum preloading technique.