ObjectiveTo establish a surface-enhanced Raman spectroscopy (SERS) method for the rapid detection of three forbidden veterinary drugs, crystal violet, malachite green, and methylene blue, as well as two pesticides, thiram and thiabendazole.MethodsPolyurethane (PU) yarn was used as a flexible substrate, and its surface was further modified with polydopamine (PDA) functional layer. The modified yarn (PU@PDA) was then immersed in a silver ammonia solution. The silver ions in silver ammonia complex can be in-situ reduced to silver nanoparticles (AgNPs) by the reducibility of PDA. This produced the PU@PDA@AgNPs composite flexible SERS substrate material. Moreover, the sensitivity of the SERS material can be optimized by changing the concentration of silver ammonia solution to control the amount of AgNPs on PU@PDA yarn. The new material was then applied in the detection of three dye based forbidden veterinary drugs and two pesticides.ResultsThe limits of detection for crystal violet, malachite green, and methylene blue can be as low as 1.0×10^-8 mol/L, and the limits of detection for pesticides thiram and thiabendazole were as low as 0.5 mg/kg and 2 mg/kg, respectively.ConclusionThis method is easy to operate, environmentally friendly, safe and highly sensitive. It can provide technical support for the rapid on-site detection of agricultural and veterinary drug residues.