Better understanding of the interaction among biofilm, soil, and water quality may produce an efficient and economic technology for improving the water management of sandy soils. At present, most soil-water characteristic curves researches were focused on the single soil medium or the medium containing single expansive solute. However, the quantitative understanding of the way biological activity alters hydraulic properties is a major key in understanding and engineering relevant systems such as soil aquifer treatment, bioremediation, and wastewater irrigation.In this study, we measured SWCCs of different particle sizes pure sandy soils ( low suction range ) by sand-funnel method and sandy soils mixed with different biofilm analogue (xanthan、humic acid and bovine serum albumin) concentrations ( high suction range) by centrifugation and sand-funnel method, respectively. The sensitivity of correlation parameters of soil-water characteristic curves obtained from Van Genuchten model was analyzed by single-factor perturbation analysis method which was the change curves of solute transport concentration caused by changing a single variable in the Hydrus-1D model.We measured the SWCCs of fine sandy soils amended with different biofilm analogues fractions. The results showed the polysaccharide fractions was significant for changing the hydraulic properties of soils and humic acid and protein materials had little effect. In addition, the percolation of humic acid with water flowing had the risk of groundwater quality pollution. For the sensitivity analysis by using single-factor perturbation analysis method, we found the saturated water content θs had important effect on solute transport to reach equilibrium concentration. Therefore, the accuracy of the VG model parameter θs should be guaranteed in the practical application of soil media affected by biological activities. Such an evaluation is useful for microbial ecology research, where the amount of water available to soil bacteria is of interest, and for the analysis and design of bioremediation processes performed in the unsaturated zone, where high bacteria and EPS concentrations exist.