Abstract: Pile-net(geogrid) and pile cap methods are always adopted in soft ground treated with rigid piles.The former is a method of composite foundation,while the latter is a kind of pile-supported embankment.And the deformation and stress characteristics of the piles in these two kinds of project are different.It is difficult to choose from the two methods for lacking of efficient comparative analysis.Due to the limitation of the methods of in-situ experiments,numerical simulation of 3D fluid-mechanical interaction and analysis of the two treatments were done.The deformation characteristics on the plane of pile top were obtained and a contrastive study was done on the stresses of the piles.