The spatial variability of permeability coefficient is a main cause for the uncertainty of seepage field. With the basis that the permeability coefficient is an isotropic random field which follows lognormal distribution, the influence of the spatial correlation of permeability on the statistics of seepage field is researched by stochastic numerical modeling. Three representative correlation functions, such as exponential, gaussian and spheric models, are adopted. The sensitivity analyses to variance of hydraulic head for above three models are conducted respectively with correlation distance and variation coefficient of permeability as variable factors. The results show that the choice of correlation model and the value of correlation distance and variation coefficient have an important impact on variance of hydraulic head.