Three kinds of different phases of Mg-xLi-1Al alloys with x=5 （full α LA51）, 9 （dual-phase LA91）, and 14 （rich-βLA141） were prepared by vacuum melting method. Their microstructure and damping capacities were investigated by optical microscopy, X-ray diffractometry, and dynamic mechanical analysis. The results show that the addition of Li changes the crystal structure of the alloys and causes new damping mechanisms to emerge. And the appearance of BCC structure makes the damping performance improved remarkably. The lower the elastic modulus is, the smaller the strain is and even the slower the acceleration is. The dual-phase alloy shows a better damping capacity while the temperature changes. Furthermore, all three alloys have two significant peaks：P1 caused by the movement of dislocations on the basal planes and P2 caused by the sliding of grain boundaries.
