Interference method is introduced to study the Fowler-Nordheim tunneling current oscillations. An accurate and simple formula for measuring the oxide thickness and the electron effective mass in the conduction band of the oxide is given.A comparison between the results calculated directly from the Schrdinger equation and those from the interference method for the triangular barrier case shows that the interference method suits very well for studying Fowler-Nordheim tunneling current oscillations.The interference method reveals the wave nature of the electron tunneling in the barrier.An important feature of this method is that it may be applicable to various shapes of potential barriers and wells. We also analyze the experimental results and give the physical meanings of them.