Porous material is a new type of lightweight structure-functional material with high damping performance, low density, light weight, and other characteristics, making it useful in many applications. Mg97Zn1Y2 with long-period stacking ordered phase (LPSO phase) as a matrix, MgCO₃ as foaming agent and SiC as tackifier was used to prepare magnesium-based porous materials by melt-foaming method. The mechanical properties and damping properties of the porous Mg97Zn1Y2 were studied by OM, SEM, XRD and DMA technology. Results show that the porous Mg97Zn1Y2 composites are mainly composed of magnesium matrix (α-Mg), LPSO phase and SiC phase. When the strain amplitude is small, the damping value of porous Mg97Zn1Y2 composites is obviously better than that of Mg97Zn1Y2 alloy, and the damping properties are improved as porosity is increased. However, increased porosity decreases the compression properties of porous Mg97Zn1Y2 composites. In addition to the dislocation damping, interface damping, and grain boundary damping of the Mg97Zn1Y2 alloy, “gas phase” damping is found to affect the damping properties of the porous Mg97Zn1Y2 composites jointly.