Abstract: Analysis of the performance of CFG pile composite foundation found that a plastic deformation zone surrounding the CFG pile composite foundation with an area of about one time piles distance was formed, and it is the main cause of instability of the whole composite foundation. Comparative analysis of characteristics as stress change, foundation settlement of the composite foundation before and after adding a row of fender piles in the plastic deformation zone, found that foundation performance get obvious change after pile enforcement. In the same conditions, the foundation settlement reduced significantly and the stability improved obviously.