The Magnesium phosphate cement was prepared from MgO and NH4H2PO4. The changes of the strength, appearance and hydration products of the magnesium phosphate cement were investigated, which are soaked in sulfuric acid solution, sodium hydroxide solution, sodium sulfate solution and magnesium sulfate solution. Besides, the impermeability and salt frost resistance of magnesium phosphate cement were analyzed. The results show that magnesium phosphate cement has good resistance to sulfate erosion, especially the anti-corrosion ability of magnesium sulfate. However the alkali resistance of the magnesium phosphate cement is poor. Therefore, the magnesium phosphate cements are not appropriate to be used in alkaline environment as cementitious material. The resistance of the magnesium phosphate cement to chemical attack is closely related to the stability of the hydration product MgNH4PO4• 6H2O. The magnesium phosphate cements have good impermeability and salt freezing resistance.