▎ 摘　　要

The electronic transmission spectrum of a graphene nanojunction formed by interconnecting two armchair-edged graphene nanoribbons is obtained by the first principle calculation. We find that in such a simple structure the electronic transmission is remarkably spin-polarized when its size is not very small. By calculating the local density of states and electron occupation numbers on some typical atoms at the scattering region, we conclude that the origin of the spin-polarization is the antiresonance effect, generated by the edge state localized at the zigzag-edged shoulder of the nanojunction.