Surface enhanced Raman scattering (SERS) is a non-contact, non-destructive and high-sensitivity spectral analysis technique. SERS has the capability to detect molecular fingerprint and has been widely applied to the subjects of materials science, chemistry, physics, geology and life science. Compared with the traditional rigid substrates, the flexible SERS substrates can conduct in situ and on-site real-time detection of analytes on non-planar surface. However, there are still some challenges in designing and fabricating the flexible SERS substrates with high-sensitivity and reproducibility. Therefore, we provide an overview of the recent advances in flexible SERS substrates. We discuss the fabrications, performances, applications and future prospects of five different types of the flexible SERS substrates, and provide some guidance for the research of SERS substrates.