Abstract: In order to analyze the random properties of hydraulic factors of unsaturated seepage,hydraulic properties of soils were treated as random space functions,and stochastic numerical simulation for two-dimensional unsaturated seepage has been conducted by the combination of Karhunen-Loeve expansion and perturbation method.It was shown that the variabilities of water head and water content increased with the dryness of soils.The smaller the unsaturated parameter m in the Gardner-Russo model,the larger the variability of water content.The variabilities of water head,water content and Darcian flux were sensitive to the coarseness of soil texture.Anisotropy of soil properties decreased the variability of the vertical Darcian flux.Researches on stochastic theory of unsaturated seepage should be strengthened.