Porous CuO-Ag nanofibers have been synthesized via a combination of the electrospinning technique and the PVP-assisted sol-gel technique in the absence of any templates. The thermal behavior of the as-spun fibers was characterized by TG-DSC while FT-IR was employed to prove the removal of the polymer, which resulted in a porous structure. The structure and morphology of the resultant products were characterized by XRD, TEM and SEM. Porous CuO-Ag nanofibers fabricated on a Si substrate exhibited large Raman enhancement ability, which was also investigated. The SERS signals on the obtained substrate had perfect temporal stability under continuous laser radiation and a good uniform response, enabling quantitative detection of analyte azobenzene. The log-log plot of the SERS intensity to the azobenzene concentration exhibited a good linear relationship.