The application of Karhunen-Loeve (KL) expansion to simulating the soil parameters random field is researched; and the characteristics of the KL decomposition are analyzed; and the Galerkin finite element method is adopted to solve the integral equation numerically in the irregular region and for arbitrary covariance function and to simulate the anisotropic conductivity field. It is shown that the KL expansion of lower truncated terms can duplicate the spatial structure of the random field accurately. The KL expansion method is superior to turning band method in simulating the anisotropy of a random field; and it has better convergence than the spectral representation method.