In this paper, specific emphasis has been placed on exploring the effect of electric field treatment on grain boundary strengthening for Al Li alloy 2090+Ce. The relation of the tensile properties to the electric field was investigated. The results show that the grain boundary can be so strengthened as to weaken the intergranular failure. An improvement in ductility has been obtained, however, the change of strength was very little. The research results of phenomenological theory show that the solution ability of solute atoms was enhanced and the cluster gather of solute atoms and vacancy was improved by electricfield treatment.