Interfacial dead layer effect has been widely noticed in the past and was thought to be responsible for the critical thickness of ferroelectric thin film.Despite extensive studies,the ori-gin is still under fierce debate.The dead layer even exists at the perfect interface without defects and impurities.In this paper,we studied the effects of the electrode/ferroelectric interface on the polarization properties of nano-scale BaTiO3 ferroelectric capacitors by first-principle calcula-tion.