At present , scanning electron microscopy ( SEM) and transmission electron microscopy ( TEM) are mainly used to detect the precipitated phase and mechanical properties of aluminum alloy , which is time -consuming and laborious and destructive. In this paper , the laser ultrasonic nondestructive testing technique was used to detect Al -Cu-Mg aluminum alloy. By means of Variational Modal Decomposition ( VMD) , the noise reduction of the laser ul- trasonic signal in the time domain is processed , and the attenuation coefficient and sound velocity of the laser ultrasonic signal are obtained. The precipitated phase and mechanical properties of Al-Cu-Mg aluminum alloy were obtained by SEM , electron back scattering diffraction ( EBSD) and static tensile test. The laser ultrasonic signal characteristic val- ues were coupled with the precipitated phase and mechanical properties of Al- Cu - Mg aluminum alloy. The results show that the characteristic value of laser ultrasonic signal has a good correlation with the precipitated phase , grain size , yield strength and microhardness of Al-Cu-Mg aluminum alloy. This provides a new method for rapid nonde-structive testing of microstructure and mechanical properties of Al-Cu-Mg aluminum alloy.