Nitrogen fertilizers nowadays are widely used to increase crop yield. But unfortunately, they are often lost quickly by leaching because of solvability, unlimited application and irregular irrigation, so this causes contamination of soil and water resources. On this recpect the most important worry was about nitrate and many of research showed wide soil and water resources contamination of that all over the worldin recent decade. On the other hand, treating and reusing drainage water, municipal sewage and wastewater is necessary because of shortage of water resources, especially in arid and semi-arid regions like Iran. By viewpoint of organic material as drainage envelop and this fact that they require an external carbon source to sustain denitrification and nitrate removal, this study describes laboratory experiments that investigated monitoring of nitrate and ammonium removal from drainage water in a sandy clay soil that was combined with different percentages of barley straw (10, 20 and 30% volume basis). The barley straw was either mixed with soil or was applied as separate layers. All treatments were performed with three replications. Influent of nitrate for all treatments was fix and about 80mg/L during the priod of the expriments. Effluent of nitrate and ammonium concentrations of all barley straw treatments decreased with elapsed time and effect of perentage and composition method of barley straw and soil was significant (p 0.01). Optimum volume percentage of barley straw was 20 and 30% for layered and mixed treatments and nitrate removal percent was 81, 71% respectively. Optimum treatment in experiment was 20 percent of barley straw that combined in layering method with soil. Statistical comparison between mean of ammonium concentrations in the effluent of different treatments showed that however ammonium concentrations in drainage water of treatments decreased with elapsed time and this value of concentration (less than 2.5 mg/L) and variation of it was very low, but there was significant difference (p 0.01) between the treatments in this recpect.The pH (with a range of 7.18-7.95) and electrical conductivity (EC) (with a range of 0.532-0.581 dS/m) didn’t have special trend during the experiment and there was significant difference (p 0.01) between the effluent pH treatments and no significant difference (p 0.05) between the effluent electrical conductivity of treatments. The effluent pH of drainage water for all treatments was almost lower than influent value of it but, the effluent electrical conductivity of treatments was almost equal to influent value of ti. According to this result of experiment application of barley as bioreactor to nitrate removal from drainage water especially in layering method in sandy caly soil was recommended because of this organic material had sufficient carbon to sustain denitrification, ease avalibility and low cost application of that. Keywords: Barley straw, Bioreactor, Contamination, Denitrification, Fertilizers , Nitrate .