Phytoremediation is recently paid attention as one of the low-cost and sustainable methods especially for remedying heavy metal contaminated ground. However, there are several cases that it may not be effective because plant growth is often dominated by geotechnical and climatic environments. To perform this method efficiently and effectively, it is necessary to evaluate the relationship between plant growth and geo-chemical and physical environments. Therefore, authors developed “geo-environment – plant root growth simulator” in order to estimate the future distribution of chemical substances in the ground. The explicit-finite-difference-method was applied on the simulator. The movement of soil moisture and water soluble substance can be modelled by Richard’s equation and advection-dispersion-equation. As a targeted pollutant, hexavalent chromium (Cr6+) was chosen. This paper conducted a parametric study with changing three parameters such as the initial length of root (L), solute absorption speed of root (Kp), and root length density (Lv2) about the movement of chemical substances in unsaturated ground on a cylindrical coordinate system. As a result, in this numerical condition, the initial length of root had the largest effect for phytoremediation in the three parameters.