The groundwater remediation was modeled by using zeolite, anthracite, haydite, activated carbon, steel slag, slag, coal-dust ash, and Fe0 as filling materials and six Permeable Reactive Barriers (PRBs, reactor1, 2, 3, 4, 5 and 6 respectively) were designed to research on the leachate-polluted groundwater. Experiments on the variation of NH4+ in leachate-polluted groundwater under the condition of PRB remediation were modeled for three stages and the mechanisms of NH4+ variation in reactors were discussed. The results showed that the removal rates of NH4+ were low, zeolite reactor for denitrification was better than others, and its ability for removal rate of NH4+ was 49.8%, negative values for denitrification were observed in some reactors, which may be caused by the hydrolysis and acidification since they could produce NH4+ and organic acids. The above results proved that actual treatment capacities of filling materials were not expressed fully the experimental results. Therefore, PRB technology for the treatment of leachate-polluted groundwater is feasible under the condition of further study.