Abstract: Nitrate(NO-3) is widely distributed in the water environment, and induces many problems. A platinum inter-digitated array (IDA) microelectrode modified with copper clusters has been developed to enhance the performance of the electrochemical sensor for nitrate determination. The IDA microelectrode was fabricated by Micro Electro-Mechanical System (MEMS) technique. The copper clusters electrodeposited on the IDA microelectrode are porous and have large surface area. The electrochemical performance of the modified microelectrode for nitrate determination was characterized by using linear sweep voltammetry in three-electrode system. The linear range of the copper modified IDA microelectrode for nitrate (N-NO-3) determination was from 0 to 2 mg/L with a linearity of 0.999 and a sensitivity of -3.15 ALmg-1. The IDA microelectrode with sensitive area of 1 mm2 possessed a higher electrocatalytic activity and superior sensitivity for nitrate determination than the disk microelectrode with indentical area due to the structure and edge effect of IDA microelectrode.