Surface-enhanced Raman spectroscopy (SERS) technology was performed by employing a paper-based SERS substrates for rapid detection of Scarlet 808 (S808),an illegal dye in cinnabar.The theoretical Raman spectrum of S808 was calculated and characteristic peaks of S808 were assigned to the corresponding vibrational modes by density functional theory.For preparing the paper-based SERS substrate,the liquid-liquid interface self-assembly technology was used to assemble the silver nanoparticle on the filter paper.The substrate showed good reproducibility in the test.S808 on cinnabar was detected by paper-based SERS substrates,obtaining the minimum detection limit of 0.05 μg/mL.In addition,under the concentration ranging from 0.05 to 1 μg/mL,the Raman intensity of S808 SERS spectrum with its concentrations of S808 in cinnabar displayed a linear relation,with the coefficient of R2=0.98673.Therefore,the paper-based SERS substrates can be applied into on-site detection of the illegal dye in cinnabar in an easy and rapid manner.