▎ 摘　　要

We investigate the band structure of narrow armchair-edge graphene nanoribbons (AGNRs) under tensile strain by means of an extension of the Extended Huckel method. The strain-induced band gap modulation presents asymmetric behavior. The asymmetric modulation of band gap is derived from the different changes of conduction and valence bands near Fermi level under tensile strain. Further analysis suggests that the asymmetric variation of band structure near Fermi level only appear in narrow armchair-edge graphene nanoribbons.