This article has been investigated the use of FFT for adhesive joints analysis between metal sheets. The method is based on the measurement of the reflection wave at the metal/adhesive interface. After describing briefly the physical aspects of the phenomenon, an index is defined to detect defective zone of the joint(both for the lack of adhesive and for insufficient adhesion): the influence of the experimental variables(variable stress...) on the measurement is discussed. By means of a control experiment it is shown that stress variation in adhesive joints are separate to be distinguished. In this paper, Nondestructive evaluation in adhesive joints are evaluated together with ultrasonic testing and finite element analysis.