Abstract: Spatial variability is the inherent nature of soil, which needs to be considered when calculating the bearing capacity of piles. Different coefficients of variation and correlation distance will be considered. Based on the numerical method, the existing simulation method of random field will be used to generate soil parameters so as to study the effect of spatial variability of soil strength on the horizontal bearing capacity of a single pile. The results show that after considering the spatial variability of soil strength, the average value of the single pile horizontal bearing capacity is significantly less than that obtained by the deterministic analysis, and the single pile foundation designed by the standard method is still possible to fail; the correlation distance has no significant effect on the average value of the single pile horizontal bearing capacity, but the standard deviation of bearing capacity increases with the increase of the correlation distance; with the increase of the coefficient of variation, the average value of the horizontal bearing capacity of the pile foundation decreases, while the standard deviation of the bearing capacity increases. The distribution law of horizontal bearing capacity of the pile foundation considering the spatial variability can fit log-normal distribution. According to this law, the failure probability of the pile foundation under any load can be obtained.