The foundation of the release sluice of Yakou hydro-junction in Hanjiang River project is uneven sandy gravel soil.The foundation surface is partly a thin layer of fine sand,and the sandy gravel soil contains a fine sand lens or large pebble locally.In view of the problem of large settlement and uneven distribution of sandy and gravel soil,a treatment scheme for the composite foundation with long spiral drilling and grouting piles was proposed,furthermore the pile forming test was carried out in representative areas of the site.The results show that the foundation treatment scheme is feasible,stable in quality and environmentally friendly,suitable for the application of the project and valuable for popularization.