Photofragment NO+ excitation spectrum of N2O+ ions has been studied in the wavelength range of 278-328 nm, where the parent N2O+ ions were state-selectively prepared at the X (2)Pi(1/2,3/2)(000) levels by [3+1] multi-photon ionization of jet-cooled N2O molecules at 360.55 nm. The spectrum was attributed completely to the A (2)Sigma(+)<--X (2)Pi(3/2,1/2)(000) electronic transition of N2O+. Totally 47 vibronic bands associated to 24 vibrational levels of the A (2)Sigma(+) state were identified in the present work, most of which were observed for the first time. The sufficient spectroscopic data made it possible to investigate the Fermi-resonance between the nu(1) and nu(2) vibrational modes at the A (2)Sigma(+) state. Based on the assignment, the spectral constants of the A (2)Sigma(+) state, such as vibrational frequencies, anharmonic constants, and Fermi interaction constant, were determined with relatively high reliability and precision. (C) 2003 American Institute of Physics.