By introducing an inorganic foamer, a new type of magnesium cement with high strength and water resistance is applied as the base material to prepare a series of light magnesium cement foamed materials with excellent properties and a density of 0.15-0.60 g/cm3 by the process of foaming, compacting, solidifying and lastly gelating as well as forming the closed porosity materials. After measuring systematically the properties of light magnesium cement foamed materials, the phase compositions were studied by XRD patterns. The results are discussed and conclusions drawn. The material can be used as a light wall board material, thermal insulation material, and sound insulation ceiling material. 4 refs.