Abstract: The existing theories and experience of pile foundation are based on the flat slopes, and the stress characteristics of undercompacted slope piles are quite different from those of flat slope piles. Based on the stress characteristics of slope piles, three groups of centrifugal model tests are carried out to study the bearing characteristics of foundation piles under vertical loads. The distribution characteristics of side friction resistance, axial force, vertical displacement of piles and the settlement laws of soils around the piles are obtained. The influences of compaction degree and slope ratio on the uncoordinated deformations of the piles and soils are analyzed. The results are as follows: (1) The stress of the undercompacted slope piles includes the positive friction resistance at the pile side, the negative friction resistance at the pile side, the resistance at the pile end and the sliding force of the slope. (2) The compaction degree of soils has a great influence on the distribution of pile side friction along the depth and pile tip resistance. The slope gradient has a great influence on the distribution of pile side friction resistance and the peak value of side resistance. (3) The neutral point of the negative friction resistance of the slope pile is about 0.5 ~ 0.6 times the length of the pile along the burial depth. According to the conventional design, the additional negative friction resistance and lateral load of the piles are easy to cause pile damage.