Application of ultrasonic guided waves generated by piezoelectric smart transducers has become one of the widely-used techniques in structural health monitoring. This technique has led to significant improvements and profound effects in the field of aircraft reliability and safety. Lamb wave propagation on composite plate-like structure undergoing mechanical testing is investigated in the paper. Smart PZT actuator/sensor is bonded on the carbon-fiber and glassfiber epoxy composites, which are subjected to tensile and thermal stress tests. The acquired results indicate the changes in scattering waves in composites materials due to the applied thermal and tensile force. Wavelet analysis was incorporated in this research work in order to distinguish different structural status.