Submarine pipelines are often constructed for the submarine oil & gas transport,offshore deepwater blowdown and the water intake and outlet of coastal power plant,etc.The deformation and destabilization of seabed induced by the wave,tide and other hydrodynamic factors is one of the key problems in the design of submarine pipelines.The integrated density of large-diameter pipes is often less than the natural silt density,and the pipes buried by the original silt may occur floating.Under the action of the wave,liquefaction of the overburden soil and floating of pipelines may occur,which lead to accidents.By studying the changing law and scope of the backfill’s density,and the liquefied law of sandy soil,we analyze the risk of pipeline’s floating in the specific project.