The development of the bay area is restricted by the cross-sea comunacations. Recently, the bridge-tunnel system is a perfect solution for this question. The man-made island is a key connector in this system by connecting the bridge and tunnel, and creats a buffer zone of the comunacation. The plug-in steel cylinders are suitable structure for the constructure of the man-made island due to its convenience, reliablity, and low-cost. In practice, the sand layer and other hard soil layers challenges the piling of the cylinders, causing the structure failure of the cylinder and other problems. The pre-treatment with DSM (deep slurry mixing) technology is a effective way to improve the piling process. This paper models and analyzes the piling of the cylinder through the sand layer treated by DSM technology with in-site tests and numerical simulation method. The advantages of the DSM technology are highlighted and quantificated to make a contriobution in practice.