Abstract: Based on the analysis of the geology of levee foundation and hydrologic geology,in order to understand the reason of seepage failure occurred in the levee foundation,the complex levee foundation was divided into three kinds,and the simulation experiments were performed.The failure characteristics and influencing factors of seepage were studied for uniform sand foundation in laboratory.It was found that seepage filure of uniform sand foundation mainly occurred in the contact zone of levee and levee foundation,and the failure hydraulic gradient was dependent on the failure hydraulic gradient of sand seam.When there was declutch problem,the failure hydraulic gradient became the washing hydraulic gradient on surface of sand seam.