Porous materials as a new type structure and functional materials, duo to specially structure compared with the dense materials, which given the excellent properties of materials. The powder metallurgy with space holder technique was used to prepare magnesium foam. The porosity increases from 38.90% up to 57.50%, resulting in that the elastic modulus decreases from 8.50GPa to 3.30GPa, and resulting in that the yield stress decreases from 24.90MPa to 9.40 MPa. Magnesium foam has lower yield stress and longer stress platform, so it can be used as excellent cushioning energy absorbing materials.