Composite foundation formed by cement agitation piles is used in strengthening dike foundation for improving the stability of dike project.The strengthening mechanism of cement agitation piles is analyzed along with the way in which composite foundation bears external loadings.The weighted area method is adopted to calculate the shearing strength of composite soil

with which the composite foundation stability is calculated.In connection with a case example of a river repair project

improving effect of cement agitation pile is discussed and the dike stability under different working condition is evaluated.The results of study indicate that cement agitation pile can improve effectively the bearing capacity of foundation and the stability of dike

and takes a short construction time and performs well after construction.Thus this procedure of dike stabilization can serves as a reference for other similar projects.