Abstract: The revised density method is improved based on analysis of interactions between ground soil, fill and piles in flow sliding. The density of fill outside the center of sliding surface needn’t be revised. The density of soils among piles outside the center of sliding surface is increased due to the positive frictional stress over the tensile neutral plane and decreased due to the negative frictional stress below the tensile neutral plane. The influences of tensile strength of piles on position of the tensile neutral plane and the revised density of soils among piles are taken into account. The counterforce of end resistance of piles is transformed into the soil density below piles. It is shown by analysis that the safety factor of stability is affected little by change of the revised method for density of fills and soils among piles outside the center of sliding surface, but is obviously affected by the revision of density of soils below piles when there is soft substratum. It is shown that the results of stability analysis of a sliding project by the improved revised density method for rigid-pile composite foundation coincides with the project practices.