The FSL agent for soil infiltration prevention developed by Nanjing Forestry University after many years’ studies is a new type of strengthening and harmless soil infiltration prevention agent.It shows a broad prospect for application to desertification control and water resources conservation. Itsmain comoosition is vegetation renin(high content in tanin extract ),water glass and molysites. The agent has goob affinity for sands. Chain, coordination and polymerzation will take place under suitableconditions. It can be used both by grouting and spraying. The agent will gelatinate high polymer skeletons between soil pores and the soil surf see and form organic-inorganic-soil artificial complex hydrophilic materials. Thus, soil infiltration is prevented. In order to get the best results, the composition of the agent of the order of grouting can be adjusted according to water quatity, soil type and infiltration rate. It Can be used for sand fixation, water conservation, sand plantation and infiltration prevention of salt pam in semiarid and semihumid regions. It can also be applied to the treatment ofsewage water, POllution control of river bed-soil and treatment of urban coal ash.