Graphene nanoribbon(GNR),a building block for grapheme-based nanocircuit,is a very simple but interesting physical or chemical system.The properties of a GNR,unlike other quasi-one-dimensional quantum wire system,is sensitively dependent on its edge details and the number of carbon chains contained.In this talk I will give our two recent works on pristine GNRs.One is the electronic structure and transport property of atomic chains in GNRs,and the other is the atomistic structural response to external strains.