The optical character of the multiplayer system with a negative refractive index layer is investigated. By means of a transfer matrix method, the exact analytical expression of transmissivity has been derived. Unusual photonic tunneling in the multilayer system with a negative refraction index layer has been analyzed. For all frequency and incident angle, if all parameter are matching, the transmittance reaches unity. When only the backdrop is not matching, the transmittance is independent of the incident wavelength, but depends on the incident angle. For the TM wave, there is a special angle, known as Brewster's angle, with which the transmittance reaches unity, and a larger refractive index of the end will enlarge the transmittance. When the thickness or the refractive index of the medial layer is mismatching, the transmittance distributed symmetrically about the mismatching position decays with the increase of the disharmony, and there appears a faster decay when the incident angle increases.