By performing first-principles electronic structure and transport calculations, we have demonstrated the electronic structure and transport properties of single layer zigzag graphene nanoribbons with armchair edges and the effect of edge-vacancy defects. It is shown that perfect zigzag graphene nanoribbons are semiconductor with certain energy gaps which will become smaller due to the edge-vacancy defects combining with semiconductor-metal transition. This result may contribute to the electronic structure sewing of the graphene nanoribbons in the energy-band engineering.