The magnesium salt and sulfate attack of cement based materials under electrical field and low temperature environment was studied by corrosion damage grade of TSA, compressive strength ratio, SEM/EDS, FTIR and XRD. The results indicate that cement based materials are significantly corroded in a cathode Na2SO4 anode MgSO4 compound， the next was in a cathode MgSO4 anode MgSO4 compound and cathode MgSO4 anode MgCl2 compound. The corrosion of magnesium salts in both cathode and anode is inferior to the case where magnesium salts does not exist in cathode. The water was electrolyzed to OH- reaction with magnesium salt to Mg(OH)2 under the electrical field of cathode when there was magnesium salt in cathode. Mg(OH)2 will jam the surface of sample which results in delaying the migration of SO2-4 and magnesium salt would continuously corrode C S H gel which results in the production of surface crack to accelerate the corrosion of cement based materials.