This work presents a bulk electrode and a microband electrode array for electrochemical nitrate sensing in acidic medium. The microelectrode array is fabricated on silicon wafer by micro electro-mechanical system technique. Electrodepostion was carried out to modify tin onto the bulk palladium electrode and thus formed Pd-Sn bimetallic composite. On the microelectrode array, Pd and Sn were successively deposited to obtain a double-layer composite. The performance of the two kinds of electrodes towards nitrate sensing was investigated and compared. The microelectrode array showed better sensitivity and repeatability than the bulk electrode. The results are consistent with the unique properties of the microelectrode array in electrochemical analysis such as high current density and low background noise.