Abstract: The action mechanism of electric field on pure aluminium deformed at 480 ℃ was studied mainly in term of dislocation structure.The microstructure and fracture was analyzed by optical microscopy and SEM.The results show that the application of electric field resulted in the decrease of flow stress,yield strength and dislocation density during the high temperatre deformation process of pure aluminium.The electric field also suppressed the nucleation and growth of internal cavities in the tension deformation process,and increased the tensile elongation.The intensity and polarity of applied electric field affected the dislocation movement in elevated temperature tension deformation process of pure Al.