Molecular dynamics (MD) simulations were performed to study interaction between the graphene nanoribbon (GNR) and single-wall carbon nanotube (SWCNT). The GNR enters the SWCNT spontaneously to display a helical configuration which is quite similar to the chloroplast in the spirogyra cell. This unique phenomenon results from the combined action of the van der Waals potential well and the π-π stacking interaction. The size of SWCNT and GNR should satisfy some certain conditions in the helical encapsulation process. A DNA-like double helix would be formed inside the SWCNT with the encapsulation of two GNRs. A water cluster enclosed in the SWCNT has great effect on the formation of the GNR helix in the tube. Furthermore, we also studied the possibility that the spontaneous encapsulation of GNR is used for substance delivery. The expected outcome of these properties is to provide novel strategies to design nanoscale carriers and reaction devices.