Nowadays environmental pollution is one of the most serious issues that various communities have to deal with. In their daily routines, human beings enter significant amounts of pollutants to water, soil and air, witch are considered as the major components of the environment. Unlike water and air, soil pollution is not easily measurable in terms of its chemical compounds and so pure soil is not definable. Since mid 1980, soil contamination caused by hydrocarbons has been considered as an environmental crisis. But, unfortunately in our country there has been no serious studies about contamination spreading and methods for controlling it, so far. The major part of contamination spreading is caused while the pollutants reach the aquifers, their dissolvable substance dissolve in water and contaminate the media along with the water. Therefore the importance of studying contaminations spread and finding methods to prevent them from reaching aquifers become evident. This thesis consists of two parts. The first part deals with laboratory experiments, while the second part is about modeling the flow and traort of some hydrocarbon pollutants. In the experimental part, with use of a specially apparatus for this study, permeability of water and petroleum, permeability of petroleum in the wet-water media with various saturations (less than residual saturation), and also permeability of water in the wet-oil media for various saturations (less than residual saturation) were measured. These experiments were conducted for two different kinds of soil with three different densities. To achieve the devised densities, the pluvial (raining) method was applied. At the end of the experiments, permeability of water was found to be higher than the same permeability for petroleum. The experiments also showed that permeability of water in various wet-oil media decreases with increasing saturation of petroleum (less than residual saturation), whereas the permeability of petroleum in various wet-water media increases with increasing saturation of water (less than residual saturation). At the end of the experiments a new quantitative method for determination of wettability was introduced. To calibrate the new apparatus, the permeability was also measured with the usual laboratory device and was observed a good correspondence between the two serious of experiments. In the second part of this thesis, the spreading of benzene, 1-3 dichlorobenzene and 1-2-4 trichlorobenzene in three different kinds of soil were studied, using the 2-D software MOFAT. In this section the effect of kinds of liquids, sort of soil used, the amount of injected fluids, and also time upon the spreading of NAPL in vadose zone were studied and related diagrams along with an interpretation of the results are presented.