Abstract: Lab model tests on pile groups in sands with different density are performed, which could provide necessary parameters and macro according for PFC modeling. Then some macro properties of pile-soil are analyzed. On such a basis, the particle flow code analysis models of pile groups are established. Some macro phenomena of lab model tests are verified. The influence of behaviors of pile groups with different pile intervals and cap stiffnesses from the micro level is analyzed. At last, the distribution of load on piles is analyzed. The particle flow code simulation results and the previous conclusions can provide the theoretical references for the design and construction of the settlement-control composite pile.