2A14 aluminum alloy is the important raw materials of aerospace, which belongs to the heat treatment aluminum alloy. Friction stir welding (FSW) can weld aluminum alloy with high quality, and can avoid the pores and cracks of fusion welding effectively. In order to obtain better mechanical properties of FSW joints, the surface nanocrystallization method is introduced into FSW technology. By means of the hybrid surface nanocrystallization (HSNC) method of both supersonic fine particles bombarding (SFPB) and surface mechanical rolling treatment (SMRT), a smooth gradient nanostructured (GNS) layer was formed on the surface of 2A14 aluminum alloy before FSW. The FSW joints microstructure and fracture morphology of the original and HSNC specimens were researched by OM, SEM and TEM. The results showed that nanostructure layer zone (NLZ) was formed when GNS with shape similar to the "S" line was distributed in the thermal-mechanical affected zone (TMAZ) and the nugget zone (NZ) of the HSNC specimen. The lowest micro-hardness and fracture position of the original specimen occurred on the TMAZ of advancing side (AS). The lowest micro-hardness and fracture position of the HSNC specimen occurred on the NZ. The tensile strength of HSNC specimen was 6.4% higher than the original sample. The elongation of HSNC specimen was 14.1% more than the original specimen. The fracture mode of both specimens was toughness fracture. The fracture morphology of the HSNC was isometric dimple when the fracture morphology of original specimen were non-isometric dimple and avulsion dimple. Analysis showed that the NLZ of the FSW joints was beneficial to improving the strength and the plastic deformation capability simultaneously.