Abstract: Three centrifugal model tests are carried out, and the axial force of piles, side friction resistance, pile-soil stress ratio and moment of piles under different loads are compared. The test results show that when the additional loads on the composite foundation increase: (1) The axial force of piles and the increments caused by the excavation increase obviously, and the value of pile side friction increases under the same direction. (2) The pile-soil stress ratio and its increment obviously increase. (3) The bending moment of piles under the excavation conditions increases correspondingly, and the effect of the load is gradually reduced as the distance from the foundation pit increases. (4) With the heavier additional load, the soil between piles is more susceptible to the disturbance of the excavation, and the load is more transferred to the rigid pile, so the axial force of piles increases, with the larger bending moment of piles, the demolition tendency of the piles is accelerated. The conclusions can provide reference for the design of retaining structures adjacent to the existing composite foundation, and the lateral displacement of the composite foundation should be strictly controlled.