Abstract: The inclined pile under vertical load may yield large horizontal displacement, deflection and bending moment. Consequently, bending failure may happen before the ultimate bearing capacity of vertical pile provided by soils is fully mobilized. Based on the field test results, numerical simulations are carried out to analyze the influence of surface soil improvement on the behavior and capacity of inclined piles. The results indicate that the depth, area and location relative to the pile of the treated soil may affect the behavior and failure mechanism of inclined piles under vertical load. The improvement of shallow soils can provide significant lateral support to piles and thus reduce their horizontal displacement. In addition, the treated soils can reduce the rotation and deflection of piles. Both of the two effects can prevent the inclined piles from bending failure before penetration failure happens. Large elastic modulus of the treated soils can better reduce the horizontal displacement, deflection and bending moment of piles under vertical load. However, there is an optimum value, i.e., when the elastic modulus is larger than it, the reinforcement effect no longer increases.