Abstract: A stochastic partial differential equation of water flow in saturated unsaturated formations is developed with the soil and aquifer conductivities treated as the random fields.The variability of water head resulting from the random roil parameters are analyaed based on the stochastic numerical rmdel.It is shown that the water head variability increases with the increasing soil parameter variability and its correlation length.The variability of water velocity is large in:direction and small at the pumping point when there is a pumping well in the simulation domain.The unsaturated parameter a in the Gardner model has larger effect on the variability of pressure head and water content than the saturated conductivity of the soil.The simulation resups indicate that the smaller the water content,the larger the variability of water content.The application of the stochastic numerical model to the analysis of the reliability of groundwater flow is also discussed.