Four difference designs in sizes and configurations of screen-printed electrode (SPE) printing on a substrate of polyacrylic sheet, were investigated. The working and counter electrodes were printed by carbon ink while the reference electrode, conducting track, and insulator were printed by silver/silver chloride, silver, and insulating inks, respectively. The electrochemical signal of Fe(CN)6 3-/4- was used for selection the best SPE design. The selected SPE was modified by Cu nanoparticle as a catalyst by cyclic voltammetric method on the working electrode for determination of nitrate. The Cu nanoparticles on that working electrode were characterized by scanning electron microscope. Cyclic voltammetric and square wave voltammetric methods were performed to evaluate the performance of nitrate sensor. The nitrate sensor response was linear over the range in three orders from M to mM, with high sensitivity and low detection limit (0.3 M)