In the current paper, the nonlinear mathematical expression between porosity and hydraulic conductivity which describes saturated and unsaturated seepage of water in soil was developed for researching the effect of porosity on pollutant distribution in soil. The pollutant distribution in a rectangle vertical section was simulated by considering 0.2, 0.4 and 0.6 porosity. The numerical simulation results show that the porosity has important effect on the transport of contamination in soil. The increase of the porosity led to the increase of the water content in soil, and the increased of the diffusion rate and transport speed. Since, the hydraulic conductivity is in proportion to the porosity, the larger porosity led to the larger hydraulic conductivity, and the pollutant was easier to transport downstream.
