Supported noble metal nanocatalyst is an effective way to improve the utilization rate of precious metal catalyst for the economic cost reduction, and is also a new potential surfacing enhanced Raman spectroscopy (SERS) substrate material. In this paper, reduced graphene oxide (rGO) reinforced polyacrylonitrile/polyaniline fibers (PAN/PANI/rGO) were first fabricated by electrospinning technology. Au nanoparticles were then grown on the surface of as-prepared PAN/PANI/rGO fibers by in-situ reduction method. The structure and morphology of the final formed PAN/PANI/rGO/Au fibers were characterized by SEM, FTIR, XRD, XPS, Raman and UV-Vis spectroscopy. The catalytic reduction of 4-nitrophenol (4-NP) in the presence of NaBH₄ in water was used to evaluate the catalytic and in-situ SERS detection properties of the synthesized PAN/PANI/rGO/Au fibers. Compared with PAN/PANI/ Au and PAN/PANI/GO/Au fibers, the results show that the prepared PAN/PANI/rGO/Au fibers has the best catalytic activity, in-situ SERS detection ability and cycle performance.