In order to investigate the interaction behavior of pile-raft-soil from the microscopic view, the pile model test was carried out by adopting digital image correlation method, and the load-settlement curves, visualized displacement field beneath cap were obtained. The three dimension displacement field was got from the numerical analysis of ABAQUS. The study results showed that the load-settlement curves descended slowly,and the following load of ordinary pile foundation was taken by the piles. As for composite pile foundation, the following load was taken by the soil beneath cap, and presented more behavior of raft foundation. The displacement influence region of ordinary pile foundation such as in length and width was smaller than composite pile foundation. The compression region was mainly centralized beneath the pile tip to ordinary pile foundation，which presented a destruction pattern of block deep foundation. As to composite pile foundation，the compress region of soil around pile gradually became the dominant position, and the compress region of soil under pile tip became more and more small, a triangular compression zone existed immediately beneath the cap, which presents a displacement pattern of single cap. With the increase of pile space, the influence region of lateral soil deformation transfered from pile tips to the soil among piles, and got a maximum at a certain depth under cap. Composite pile foundation was destroyed by the lateral squeeze of the soil around piles.
