Abstract: The homogeneous random field model for soil parameters is widely used in the reliability analysis of slope stability. In this model, it is assumed that the fluctuation scale of the soil parameters is constant. However, for the slopes with different soil types, especially those with local weak layer, the homogeneous model can not effectively simulate the influences on the slop stability by the weak layers. Therefore, a non-homogeneous random field model for soil parameters with multi fluctuation scales along the depth direction is proposed. According to the stratification characteristics of a soil slope, the mean value and the variance of soil parameters are assumed as the functions that vary with depth of different soil layers. The covariance matrix of the non-homogeneous random field is constructed by exponential correlation function. By the combination of the non-homogeneous random field model for soil parameters with the plastic limit analysis method, the reliability of slope stability is analyzed for a practical project. The influences of non-uniform fluctuation of shear strength parameters such as the cohesion and internal friction angle of the soil on the critical slip surface and the reliability of slope stability are studied. According to the numerical results, it is shown that the proposed non-homogeneous random field model with multi-fluctuation scales is proper for the soil slope with several stratifications, especially for the slope with the layer of small shear strength. In contrast, the homogeneous random field model with constant fluctuation scale or the non-homogeneous random field model with linear function of mean value and variance is suitable for the slope composed of one type of soil.