The ultra-high molecular weight polyethylene (UHMWPE)/graphene (GR) nanocomposite fibers were prepared by melt-spinning. The effects of GR contents on the structure, thermal properties, mechanical properties and creep properties of UHMWPE fibers were studied. The results show that the GR in UHMWPE fiber matrix is uniformly disperse at nanometer-scale thickness. When the graphene content increase to 5‰, the GR shows large agglomerates in UHMWPE fiber matrix. Compared with that of pure UHMWPE fiber, the tensile strength and knot breaking strength of GR-modified nanocomposite fibers are significantly increased. Introducing a certain content of GR can effectively enhance the creep resistance of UHMWPE and reduce its creep rate. When the nano-graphene content is 3‰, the breaking strength increases by 31.9% and the creep rate decreases by 27.3%. When the nano-GR was being introduced to UHMWPE, the interaction between the nanoparticles and the polyethylene segment was enhanced, and the limited amorphous regions near the grain boundary increased, and the α transition peak increased and broadened gradually. The nano-modification technology can significantly improve the mechanical properties and creep resistance of ultra-high molecular weight polyethylene fibers. The results provide a theoretical basis for the high performance of fishing materials.