Standard Raman spectroscopy coupled with metal nanostructures, known as surfaceenhanced Raman spectroscopy (SERS), has exhibited great potential in detecting molecules at trace levels. Translating this profound phenomenon into practical applications requires reliable and scalable approaches to manufacture SERS-active metal nanostructures, so-called SERS substrates, with well controlled quality. Following a review on the fundamental aspects of SERS, this paper summarizes a broad spectrum of nanofabrication methods that have been employed for SERS substrates and groups these nanofabrication techniques into three categories: lithography based methods, non- lithography template methods, and direct formation. It should be noted that this review focuses on on-chip SERS substrates and the colloidal nanoparticles-based SERS substrates are not in the discussion. In the end of the review, the paper also briefly discusses several commercialized SERS substrates on the market.