Abstract: According to field test results, the interaction characteristics of cap-pile-soil and the bearing behaviors of piles and soils of the composite foundation with CFG piles with caps under flexible loads are analyzed. The following conclusions are drawn: (1) in the ultimate state, the exertion degree of bearing capacity of CFG piles with caps of the composite foundation is greater than that of the soils; (2) in the normal service condition, the exertion degree of bearing capacity of CFG piles is much larger than that of the soils; (3) the safety margin of piles is less than that of the soils.