A graphene nanoribbon (GNR) has two basic configurations when winding on the outer surface of a carbon nanotube (CNT): helix and scroll. Here the transformation between the two configurations is studied utilizing molecular dynamics simulations. The energy barrier during the transformation as well as its relationship with the interfacial energy and the radius of CNT are investigated. Our work offers further insights into the formation of desirable helix/scroll of GNR winding on nanotubes or nanowires, and thus can enable novel design of potential graphene-based electronics. (C) 2014 The Chinese Society of Theoretical and Applied Mechanics.