Abstract:  3D elasticoplastic finite element method was used to analyse the beha vior of vertically loaded pile groups by using LadeDuncan model and stiffplasti c th in unit model respectively,to simulate elasticoplastic soil body and the relat iv e movement between piles and the surrounding soil.The analytic results showed th at the obvious differences of the loadbearing characteristics of pile groups e xist for large or small pile spacings,i.e.,the surrounding friction resistance o f pile group with large pile spacing occurs "settling softening" phenomenon,whi ch is different from "settling hardening" of those with small pile spacing; To increase pile spacing is benificial to transferring load to soil under the supp orting platform and thus can increase the ratio of platform′s load to total loa d;With the increase of load,the differences of reaction on pile tops decrease,an d the distribution of total load on group piles trends towards approximately unif orm.