Recent fabrication of graphene nanoribbon (GNR) based field effect transistor (FET) has made all-carbon electronic device a reality. GNR can be metal or semiconductor with the variation of its edge orientation and width and is expected a promising material for quantum electronic devices in the future. In addition, magnetic properties which are difficult to be exploited in conventional semiconductor devices can be easily manipulated in GNRs via artificially introducing defects or doping. This great advantage together with the long coherence distance for both charge and spin in these structures has made GNR a very intriguing material for spintronics as well as electronics. In particular, zigzag GNR is one of the most attractive systems due to its peculiar edge states, which are showing ample potential in spintronic applications. Different methods have been proposed to developing useful properties of ZGNRs with the help of defects, gate voltage, chemical adsorption, doping, etc.