In this study, we compare the accuracy and applicability of laser interferometer and electromagnetic acoustic transducer (EMAT) with respect to the detection of the metal laser ultrasonic signals to detect the thickness loss and surface-breaking cracks with respect to the metals during the production and usage processes. The surface and longitudinal wave signals were detected using the laser interferometer for predicting the thickness of the aluminum plate, and the longitudinal wave signal on the back of the aluminum plate was detected using the laser interferometer to detect the depth of the defect. Surface wave signal of EMAT is used to determine the position of crack defect of aluminum plate, and longitudinal wave signal of EMAT is used to determine the thickness of aluminum plate. The results show that, compared with the laser interferometer's complex laser ultrasonic signal receiving optical path, the errors of EMAT aluminum plate thickness measurement and crack defect location detection are less than 4%. And the prediction of the crack location will not increase with the decrease of the surface crack depth. Furthermore, the obtained results prove that the combination of the laser ultrasonic technology and the EMAT method can effectively reduce the complexity associated with the detection conditions and improve the applicability of laser ultrasonic technology.